Bad attitude - breach of contract - arrogance

I just do not even want to try and talk to Cell C people anymore!!!! I specifically requested a response in writing on my query, but I keep receiving phone calls from customer service from people with either generic questions and answer or arrogant attitudes.Today I was arrogantly asked if I had asked Cell C before I stopped my debit order at my bank after I have legally, after the completion of my 2year contract, in writing discontinued the renewal of the contract. Never was any written response given (as I kindly requested opposed to phone calls), that I must make one more payment - which I would have gladly done by a cash deposit. I have sent emails directly to retentions requesting why they are still trying to debit my account, but they do not answer me - if they rep**** that one more payment should be made, I would have done it and all was concluded. Now Cell C staff is arrogant and keep harassing me over R299 which is outstanding - and may I mention, that the contract amount was increased without my consent - which was also never solved during the contract period