Bad service and I need my money back

Hello Peter, please help🙏. I opened contract with MTN on the 26 of June 2019 and the contract was for 2 years, and it expired this year on the 26 of June 2022. I went to the physical store on the 17th of June 2022 to put a notice that my contract will expire soon and they must not deduct another money next month and I was told I must call their call center and they will help me there. I've been calling them and with no response. Kept trying on calling them but still I didn't get response until they called me on the 13th of July 2022, and I told that sale agent since my contract ended or expired last month on the 26th of June 2022 I don't want to continue wth their services and remind them not to make another deduction this month, and the sale agent told me they are aware that my contract expired last month but they will take their last payment of R350 this month on the 15th. Within the period of 2 years I was paying R350 for my contract. On the 15th July 2022 MTN deducted R1170 instead of R350. When I tried to call the call center they told me that R800 it's for cancelation of contract and according to them they said I canceled my contact before the contract ended which is called breach of contract, I told them that my contract ended last month on the 26th June 2022 and I didn't cancel anything and I told them to also check their system for reference wth my profile and I was waiting on the line and they ended up telling me thy will excalate my matter to the contract department. I've tried to call several time but no help and ii need my money back.