Cancellation of Contract

I have received calls from Cell C to upgrade my contract and i informed them that I intend to cancel the contract when it expires in October 2023. I was debited in October an amount higher than what was debited before, and I reversed the debit. Today I received a call from their collections department, I still informed the person that I want to cancel my contract and I was told that I won't be able to cancel with an outstanding amount. I asked that the agent put me through to the cancellations department, they put me through to the customer service department and the agent there said she will put me through to the cancellations department only to be answered b y a voice recording informing me that the service is not available. It seems like it is very easy to take a contract with this company but very difficult to cancel the contract with them. I do not want them to debit me anymore and I have not used the sim card for a very long time because of the poor network connectivity in my area therefore I do not need the contract anymore. *** Dineo Thipe