Sometimes, customer service and/or tech support are the problem.
But sometimes, I'm the problem.
I have to reconfigure my work email today. I read the FAQ. It said to be sure to put my full email address as my username.
I looked at the config form. Yep, there was my full email address.
I called helpdesk to check on a different configuration detail, and after helping me with that, they said "Be sure and put your full email address as your username." I said I would. I looked at the config form again to be sure. Yep, there was my full email address.
I tried checking mail. Connection didn't work. Said my username and password were incorrect.
I called helpdesk back (possibly the same person answered, not sure) and told them about the error. They said, "What do you have as your username?"
I looked at the text box labeled "username." It did not have my full email address in it.
A text box above that, the one labeled "address," did have my full email address in it. That's what I had been looking at.
I explained what had happened, and apologized with much embarrassment. The helpdesk guy was very understanding about it.
I entered my full email address as the username, and everything worked.
Tech support people have a word for this kind of situation (and many other such situations): PEBKAC.
It's why they always start by asking if your computer is plugged in, and it's why a customer starting a support call with the geek handshake is sometimes a mistake (because it can mislead tech support into assuming you've already tried the easy stuff).
Anyway. It's always useful to me when I get free and painless lessons in humility; slightly reduces the likelihood of subsequent expensive and painful ones. Maybe doesn't reduce that likelihood by much, but slightly.