A customer called in earlier today for their account info, got their username and password.
The customer called back.
They can't get logged into the system for the first time.
The username and/or password doesn't work.
I verify their identify, and then confirm the username.
I spell the username out for them. The seem to accept it.
They try to login, it doesn't work.
I change the password, give the new password and confirm the username (again).
It doesn't work for them.
I ask to login as them, it works for me.
The customer finally says that the username I gave them was wrong and they were using the right one.
They didn't like the one we assigned them and thought it should be something different.
I wonder how you can support the irrational.