unauthorized debit orders on a closed account

I am very upset with Telkom Mobile Phone contract department. I settled my account last year Mid November and requested that the contract should be cancelled, and my line moved to Pre-paid.

December 2025 - A debit order amounting to R10, was ran but did not go through because I had 0 funds on the main *** January 2026 a debit order of R213 was processed again, I don't understand why because I had asked them so nicely that my account should be closed and moved to prepaid.