When someone doesnt understand and comprehend the substance or message you are conveying, but instead points out the flawed structure/composition of the way you said it, thus concluding your'e thinking flawed or wrong?

Any known bias and/or related fallacy to this?

The inability to form a properly constructed sentence is not a case of flawed logic. It's simply a case of flawed grammar. For example, your statement can be interpreted two different ways, and both interpretations result in confusion.

The first interpretation is that you make a statement that includes a compound subject consisting of three clauses: "When..., but..., thus,,,", which then abruptly ends without a predicate (i.e., without a verb and object). In other words, the first interpretation is that you write incomplete sentences.

The second interpretation is that you ask a question that begins with a compound subject consisting of two clauses: "When..., but....", which then ends with a malformed predicate: "thus concluding [that] your'e (sic) thinking [is] flawed or wrong?"

I suspect that your intention is the second interpretation. If that is your intention, my answer is you can't (or shouldn't) assume that your audience is motivated to intentionally misinterpret what you say (or write) without first asking, "Do you think my thinking is flawed?" Only then can you get an unambiguous response.

My advice: Until you develop a better sense of grammar, write in short, simple sentences and avoid compound sentences.

When someone doesnt understand and comprehend the substance or message you are conveying,

We need to take responsibility when people don't understand us. Sure, there are some people who will never get it, but a vast majority of the time this is a problem of communication about which we can do something. Restate the message. Ask for confirmation. Make sure they get it.

but instead points out the flawed structure/composition of the way you said it, thus concluding your'e thinking flawed or wrong?

This is known as the fallacy fallacy or argument from fallacy. See Argument from Fallacy 

It can be frustrating and appear as a dodge when you think you've posited a sincere question and the immediate response is an attack on your grammar or spelling, but as Dr. Bo and Mark Filipak point out the burden is on the initial claimant to state his or her question/argument as clearly, concisely and correctly possible.

According to Aristotle's Analytics a logician is under no obligation to respond to a poorly constructed premise - whatever that flaw might be (spelling, grammar, construction, logic, etc.). The general rule is that a flawed claim should be identified before it is rejected, dismissed and/or asked to be restated. While it may seem like nitpicking most of the participants in this thread examine the logical and grammatical integrity of a claim before taking the time to respond to it. They do this in order to identify the fallacy correctly rather than as a clever distraction or dodge. Unfortunately, most fallacies derive directly from an initial failure in logic, construction, coherence and or composition.

Now, if the claim is corrected and the respondent continues to distract from the argument by focusing on how the claimant arrived at their position through social status, identity, or religious indoctrination without addressing the claim itself then this could potentially tread dangerously into Bulverism and other errors in reasoning.

When you discount someone's answer because they didn't address your question as you wanted.

I tend to agree w/ the responses. In my experience, when someone doesn't express a point clearly, this is because the underlying argument is also unclear. Language is how we express our thoughts; unclear thinking produces unclear language. Sorry.

If i may, your question is worded vaguely enough to confuse me.
What you describe is the usual way we determine is something is true or not. If there are mistakes in the logic, chances are, there is a fallacy. But "points out the flawed structure/composition of the way you said it, thus concluding your'e thinking flawed or wrong?" is not a fallacy by itself. Maybe the way someone does this is fallacious, but not the action in itself.

As for biases, there are a huge number of possible culprits.
One can attack the bad points of an argument, in order to escape having to accept the good points. This often happens when cognitive dissonance is working full power. i.e. you believe something but when evidence to the falsity of your belief presents itself, you reject it emotionally or escape it by criticising irrelevant points to the core claim. Or, you modify your beliefs slightly towards what you already believe, to resolve the conflict.
More on Cognitive Dissonance here journals.sagepub.com/doi/. . .

As Dr. Bo also said, it's possible that it's a fallacy fallacy.

There's Anchoring. Which is when you base your entire models on one piece of information, to figure out an unknown proposition, and form everything around it (usually the first info about it), in terms of calculation this happens differently than in logical arguments. Therefore rejecting things that deviate from the Anchor; as for how this plays out, there isn't enough space here, BUT you can read it from here facilethings.com/blog/en/. . . it is good enough. A more in depth understanding of the Heuristics involved would require you to read some Daniel Kahneman.

Belief bias. You discount the logical strenght of the argument, by how believable the conclusion is. This happens A LOT with people who overuse Reductio Ad Absurdum. Unintuitive conclusions are hit hard the most. I have a personal bone to pick with the concept of illusions, but convincing people that the definition is wrong is hard exactly because of the omnipresence of the socratic method.

Dunning-Kruger effect. Where someone may dismiss an argument because they believe to possess the superior knowledge. This comes in the form of an Argument from Authority, or False Authority www.logicallyfallacious.c. . .

The IKEA bias (Not kidding). Where you refuse to let go of an argument because you spent time over it, made it yourself, think it is more valuable because of it, which then makes you take the defensive stance of only attacking the argument, and refusing the good points. I have a Pdf of a study on it, and it explains a lot about why people refuse to let go of their positions. Especially when they altered it, and "Made it better". You can look it up on google scholar, it was made by Michael I. Norton, Daniel Mochon and Dan Ariely.

It may stem from Post-Purchase Rationalisation. In the case of a logical argument, you have accepted an argument because it made sense (at the time), or because it helped you through tough times (optimism), understanding that it works, you keep it to you. When evidence to the argument's falsity appears, you do what is described in the question, for a combination of the IKEA effect, Emotional Investment, and the erroneous belief that even if it could be wrong under an instance, it is true and pragmatically useful under the rest of circumstances.

Honestly, there are so many. But these are some of the most recurring. Fictional worlds abuse the IKEA bias very often. "Because we spent a lot of time doing X, X is more valuable than Y."
Which we then bring up with the Appeal to Fiction (I'm kinda surprised it's not listed as a Fallacy on the site, maybe i just missed it?), where we claim something in the real world is the same as something in the fictional world, and that solutions used there are applicable in reality. You can reformulate this fallacy in a number of ways. It's really useful when you don't understand it's a fallacy. Though i don't like mentioning names, Jordan Peterson, who you might know, does this a lot. He really likes Dostoevskij.