You either have to convince Tech Support to help you solve the problem or do it yourself. When I have a problem that I need to call tech support, I just don't accept that they can't help. Ask them to elevate the problem.

I believe the best solution is deleting/reinstalling the email account. It will be the same process you used when you first set up the account.

You will need the following info:
User Name
Password
Incoming Server Name
SMTP (outgoing) server name