Paid cancellation fee. Still being debited every month.

I phoned their cancellation centre because I am not using their home internet line anymore. They made me pay a cancellation fee, and also requested that I send through proof of payment, ID document, and signed document for cancellation. I did all of that, and it all got ignored, and I am still being debited every month for something I don't use anymore. Doing some research, it turns out that Vodacom is a ****ming people and making it painfully difficult to cancel contracts. Their call centre agents lie about proceeding with cancellations when nothing happens.