Contract not cancelled on time which leads me to pay more money

I cancelled my contract with Telkom last year November the 12 and I paid the full amount on the 15 November 2024 ,to my suprise,on the 1 of December 2024 I received an invoice that show the amount that I paid and it was not cancelled,I called them and they told me that I didn't cancel.Theres a certain amount I need to pay which was R448 in January 2025 ,they deducted the amount on the 15 of January 2025 I reversed the amount because I didn't owe them because my contract was cancelled and I didn't owe them now they took me to the lawyer where I had to pay 718 and I did pay on the 17 of February 2025 but I still get messages that I didn't pay ,Telkom now didn't notify there lawyers that the payment from their side does reflect,Here's my reference ***