Payment not allocated bad service

I called l the call center to close my account and was told that I had an outstanding amount I needed to pay, I went to Markham at the Pavillion and paid that amount. When I called to cancel now that I have paid and I was told they could not pick up the payment. I was told to email the proof of payment and a copy of my ID. I have sent numerous emails to accounts department and to the customer care agents nothing has been done. One of the agent sent me an email and I rep**** to his email with the document attached, the amount is still showing on my credit score and the amount has increased since then I don't know what to do. The call center now is worse now you hold forever and they drop the call without even talking to you or helping.