First I'd check your current balance online. It may be paid now. If not then just pay the bill manually add direct debit only takes money out equal to and debit in your account. So if you've paid manually it should be $0 if anything
You'll probably have a $15 late fee and $2 non direct debit fee, both should be ready to get refunded in your circumstance.
Obviously confirm what reason there was for the DD failing. Is it possible you had insufficient funds in the bank?
Finally I agree it's a pain at the moment getting through. Seems not enough c's at the moment and too many reasons for people trying to ring.