UNFAIR debt

I had a contract with MTN, I called them last year and told them I want to cancel the contract, they gave me an amount to pay in order to close the Contract, I went to MTN shop and paid the amount given, I only received an sms to acknowledge the payment and no other form of acknowledgement of the payment. They stopped debiting till March this year and I called to ask why were they debiting cause I closed the contract the lady I was in a call with told me my contract is still active, and she gave me a case number and told me to send a screenshot of the sms I received after paying required amount, I did that and there had been no response or communication till they handled over my account. I want MTN consultants to call me and explain what game they're playing