Data prices are good but customer service is very bad

I took a data contract with Telkom mobile at the beginning of October 2020. The data contract was completed on their website and the correct information provided on the form. On the same day I received a call from a consultant and the information provided was confirmed to be correct. On the same month I enquired about the debit order not taking place on the set date via their mobile enquiry form. No respond was received back from Telkom. A month later I got a call from NuDebt debt collectors. I asked how did my name end up with them because the communication is supposed to be between me and Telkom. According to reviews on this site, this shows how the staff is so unprofessional. They got my email address wrong even my bank account number. I was penalised for the fault that they made for using incorrect bank account number and incorrect email address. I made a payment arrangement with NuDebt Trust/ecolls.co.za and the amount owed was paid in full to NuDebt on 04November. On the 06 December Telkom issued an invoice and the amount paid to their debt collectors was included. I need a revised tax invoice to be issued because, the amount due for October was paid in full.