While I've been in similarly frustrating exchanges, losing your cool (all-caps and swearing) helps nobody, including yourself. It doesn't help the already flustered and incompetent CSR help you out.
I find that in these situations, acting calmly and firmly (in this case, the only out seems to be to ask for someone more competent to talk to) is the only way out.
I'm not saying this from some sort of high-ground either. I recently had a very similar situation with Freelancer.com where someone signed up an alias to my gmail address. The support people were completely clueless and hapless when it came to 1) Realizing what the problem was and 2) Solving it. It took over a week and tens of email exchanges. I would by lying if I said my tone didn't become terse and angry towards the end.
