[whiddershins]

As another commenter mentioned, a help desk rep once gave the clue "it's really weird" over the phone, which would easily indicate to an attack to try the mash the keyboard line.

The random character thing isn't great for this use, it seems, as a result.

[ubernostrum]

If support reps give enough information away over the phone to let someone guess a security question, there is nothing you can do to protect yourself from them.