Poor service delivery

I have made payment via my nedbank app on August 25th and received a message 3 to 4 days after the payment that the did not receive the payment. I told the consultant that I did the payment and was advised to send proof of payment. I did send the proof more than three times but still can't resolve my issue instead they send me messages that I must pay. And they send messages and call almost everyday which is really boring me because I did the payment.