Need paid up letter

I'm a Telkom Client who bought Wi-fi Router ASDL at Telkom online, but unfortunately I did not receive the package as promised from Telkom. I was promised that the delivery will be on the 21 of April 2018 but that didn’t happen, and by that time Telkom was busy billing me and I tried several times to cancel it without any success. Recently, I found out that Telkom has blacklisted me when I tried to apply for vehicle finance even though the goods I purchased was never delivered, the banks advised me to pay off the account just to clear my name. We have settled the amount that was owed according to Telkom even though we never received the goods bought, now what we would like Telkom to do is to provide a Paid UP Letter that states that I paid the account in full and no longer owes it so that I can be able to continue with my life. Please help!