"Once the first "you" is said in a disagreement things usually start going downhill from there."

Another name for this would be Ad hominem argument, or appeal to personal ridicule. Its most often used by people when they run out of intelligent things to say about the issue itself, so they try to avoid the issue on its merits by instead attacking the personality of the other person.
Instead of dealing with the opponent's thesis on the merits, the fallacious argument attacks reputation and moral character; or refers to low intelligence, inferior social position, lack of education, or similar shortcomings. In the short run it sometimes works. In the long run it never works.
Here, in the short term the poster will have the satisfaction of warning other people of his difficulties. And some people will accept it. But the story is not complete. It doesn't provide the facts necessary for a disinterested person to make a factual finding of what exactly happened. And in the long run that particular business will continue on with its business, being hurt very little, if any, by what has been posted here. And the poster is left where he is, whether that is out of money, or out of a hunt, or whatever he is seeking.

A much better result would be continued negotiations based on the issue itself rather than the personalities of the parties. Maybe even a face to face meeting. Maybe with other suggestions on how the problem could be resolved. Because it sure isn't resolved now.

Last edited by 22WRF; 04/11/18.