Settled account

I got a loan with Nedbank and took a consolidation loan with Old Mutual. One of the accounts I had to settle was Nedbank. The account was paid some time in February 2014. Two months after the account was paid I received a call that I owe the bank over R4000. I emailed proof of payment and did not get any response of confirmation that it was received. In November 2014 they sent a sheriff to my workplace, I explained to him that the account is paid in full. He provided a contact number that I can use and I called to no avail. I called Nedbank and spoke to Pamella that I explained everything to her, she gave me her email address [Email Removed] I emailed her proof of payment and she never got back to me. Can someone resolve this please. This is ruining my credit reputation.