I had a problem with the password for my online banking account and called tech support about 10:00 one night. As an FYI, my passwords are always in lower case except 1 random letter which is in caps and there is 1 number. ALWAYS! We went through the same routine the OP did and it still didn't work.
The tech is speaking to me in that oh so patient/condescending voice that many take when dealing with the ignorant public. I understand that repeating the same simple instructions dozens of time to dozens of people every day can get tiring. Except that I've worked first-tier helpdesk and really didn't appreciate it and said so.
So 5 minutes into the call tech support says, try all caps. ?W?T?F? Okay, so I did and it worked. I could hear the smirk in the tech's voice as he said that I must have been mistaken about how I set my password. WRONG, WRONG, WRONG. That's not the way I set the password, never was, never will be. I said "fine, good bye" and hung up. Then I changed my password back to its proper configuration.
The next day I called and spoke with a supervisor about both the password difficulty and the tech's attitude. It turned out that when they transferred account information after a merger, my password (and thousands of others) was "adjusted" to meet their protocol. Word was the same, only the case had been changed. The supervisor apologized for the tech's attitude and said they had been receiving a lot of calls about the same thing. The techs had been instructed to explain to customers about the snafu and to try the all caps thing before doing anything else. He said that 99 out of 100 times that was the solution. If the tech I talked to that evening had done that, we'd have solved the problem in under minute and I'd have been on my way, a bit irked but satisfied with the answer. But the jerk had to take that "I'm the professional so I know everything and you,ignorant person, know nothing. Now shut up and do as I say" attitude. Bah!
[EDIT: Opening sentence has been edited to clarify my attitude.]