Debt order still going of even though proof of payment has been sent more than a week ago.

Nedbank basically *****ing money from they customers, I had a loan with them, I sent them the proof of payment that the loan has been paid up in full. They still had the nerve to go into my account and debt more money for the same loan I just finished paying for. I been on the phone with them the whole week to reverse the debt order and close my loan account this is still not done.