My seller account got banned because they retroactively added some <$1fee, and then automatically banned the account because the fee was "past due". I paid the fee, but that wasn't enough to get my account reactivated. All communications I sent seem to go into a black hole, tickets I opened were closed without any resolution, etc.

The thing that finally did it for me, was when I went to cancel my AWS account. The AWS get rep got involved, and my seller account magically got unbanned within a day.