Cell C do not respond to complain just charge you

This is the 3rd time I have to complain about the same issue, Cell C just not respond to any of my complains, just a SMS but nothing more. No one want to sort this out. <br> <br> My complain is:<br> Cell C offer me a S4 tab more than a year ago, the device did not work, I send it back twice and cancel the contract. Now they charge me for the use of this devise, I phone them and talk to 7 different people and still after an hour no success. Someone in Cell C did not do their job and it is a mission to get this sorted out. <br> <br> Cell C you better not deduct this again from my account, you stole R5 000 already from me.