Account settled

On the 16th February I settled my account and faxed the proof of payment to [Email Removed] as I wanted to make sure that this money is allocated. I was given the run around and told that the collections department needs to do this. True to my fears, I was debited today for an account I have already settled. What kind of service is that? I am really disgusted by the service I was given after numerous calls and chats to agents making sure that this doesn't happen.