Cell C NOT CANCELLING MY CONTRACT

I am sick and tired of having to FIGHT to get my ****** contract cancelled. My contract ended on the 19th of September, I've phoned multiple times to get it sorted and asked for it to be cancelled only to now be told that I have to give a further 30 days notice. This is unacceptable and I refuse to accept this. First of all, Cell C's services suck. Secondly, the "benefits" they speak of are garbage. I refuse to give a further 30 day notice when it's already been a struggle being with Cell C for over 4 years. Enough is enough. Let me pay you the different between the 19th and the 29th of September and let's part ways amicably before things get ugly. Escalation ***.