Telkom attempting to debit AFTER my account is already paid up!

Had a Telkom contract since January 2023. 07 May this year I received my final bill with a credit from Telkom as I paid this contract up before the 24 month period. I attempted to apply for another contract but there was a “block” on my account because apparently I owe Telkom one debit order instalment that apparently bounced in July. Now why would Telkom attempt to debit order AFTER I already paid this contract and closed it? Secondly, I paid in extra every month, one month I even paid a total of R4000. Why would Telkom still debit order me after THEY said my debit order has been cancelled. They requested that I send my bank statement, first they asked for 2 bank statements and when not finding any evidence of a debit order bouncing, they requested an additional 4 months bank statement and still FOUND NOTHING RELATING TO A BOUNCED DEBIT ORDER! When speaking to an agent, she told me the debit order went off in Feb but only bounced now in July, can you make that make sense? Again, based on my statement, it did not bounce and it actually went through. Telkom is a bunch of ******! I am NOT liable to pay this because my contract is paid up and it’s done! I have provided the evidence required and will not entertain this bull****! It is not MY issue if your system is an issue, you guys OWED me a credit of over R2000 and paid it to me. Now months later, suddenly I owe you? Don’t look for money! I dont owe you anything and won’t entertain any calls or emails from Telkom unless it is from management to resolve this and write this off!