Telkom - Ridiculous invoice charges

Since I have updated my cellphone contract in October 2019, at the Grove mall branch, I have never paid my bill via debit order. Suddenly in April 2021, I receive an invoice with a rejected debit order notification on my bill. I paid my bill via eft on 23 April and on 28 April Telkom decides to double bill me. Please Telkom this is ridiculous. I also tried calling your call centre numerous of times and only self service available and no option to speak to a consultant. Please fix your mistake and provide me with an amended invoice for the month of May. I will not pay the rejected debit order amount as I do pay my contract on time every month!!