CONTRACTS NOT CANCELLED

Hi. I am so tired of Cell C. I had 3 Contracts with Cell C, financially I battled and sold my second car to pay off debt, Cell C was one of them. So 11 May 2015 I phoned and asked for the settlement amounts of all 3 accounts, which I received, I then paid each contract accordingly, after paying all 3 I phoned Cell c to inform them of my payment, and asked for my settlement letters, they said that they will phone me as soon as the money clears but I must send the proof of payments through to customer service in the meantime. I never received anything from them, THEN... the last week of September 2015 I get a call saying that I am in arrears, AND Cell C tried to debit my account... So I phoned Cell C and according to them ALL 3 contracts are still active cause they cant find a call saying I cancelled... did I phone for settlement just for fun or what??? They then asked me to resend the Proof of payments.. I did so... then they said that they will get back to me..... they didn't... 3 October I get a call again saying I qualify for an upgrade, I phoned again, resent the proof of payments again, still NO ONE KNOWS HOW TO CANCEL MY CONTRACTS! I AM SO FED UP OF CALLING. CANCELL MY STUFF!!