What I got from the employees response is that THEY are in the wrong and THEY know it... and that this particular persons should NOT be their point of contact!
If she felt yelled at, she could step back, etc...and then simply ANSWER the question, without calling you out on how you typed.
I use CAPS to emphasize simply because every forum, etc has a different way to underline and italicize.
I get that all caps is yelling, but one word SCREAMS emphasis to me (and, it seems, most other sane people!)