I have only had one interaction with Unicomp's support team, and I also got the impression that the person was being rude; however, sometimes it's hard to tell if a person is being rude or just doesn't know how to write well. Some people are also just very to-the-point in order to avoid confusion. I came across the emails a little while later, and upon re-reading them, I was inclined to think I may have misread the tone at the time. Admittedly, I was very disappointed with my order, so I probably came off as unpleasant myself, but I was trying to be factual.
I worked in customer support for over five years, so I have experience on both sides. I once received an email from a customer that infuriated me; I decided to call the two guys on the phone to resolve the issue and immediately realized they were both friendly and willing to work through the problem. When I re-read the email, I realized I had completely misinterpreted the tone (probably because I had dealt with enough actual jerks prior to that). So I try to give the benefit of the doubt now.
Example:
One thing that I always interpret as rude is the ellipsis: "You should try such and such...." or "Why isn't this working..." The "..." implies to me that the writer thinks I am an idiot for not trying or fixing this before, but it seems to be something that people born between 1960 and 1980 do instead of a regular period for some reason (I guess they don't like lack of space between sentences and use that instead of line breaks[?]). I'm not trying to be ageist; it's just what I've observed. The only legitimate use of an ellipsis is to show that words are missing or that you are trailing off (which is how I interpret it).
TL:DR, yes, I have noticed this too, but I try giving people the benefit of the doubt.
