Cell C ****ed costumer

I Gave Cell C a fair chance by taking out a contract, First, the payment was the same amount for 4 months, then it went up suddenly after struggling with them for weeks of phoning the amount was fixed again. then the router they send with the package failed and I took it to Cell C Woodmead, they did not even test the device told me I must buy a new sim card, up until today the device is not working. I literally wished the two years of contract period away. Then the 6 of March I went to Cell C Kolonade to cancel my contract, the Lady explained to me that my account will be debited double by the end of March, which I understand and it was done exactly like that the end of March, end of April they debited 1100 which I reversed, they phoned me I have explained the scenario to them and then the end of May they debited nearly 300 rands which I left it like that because I thought everything is sorted just to receive a call from VVM dept collectors, Cell c handed me over saying I own them, It is really unacceptable