Cell C charging for cancelled services

I lodged a complaint with Mervyn on 12/05/2015 regarding a blackberry service fee that I had cancelled in March which CELL c continues to bill me for. He states that I had cancelled it but it was thereafter re-instated. When I asked for proof as to how and by whom, he could not provide this and said I must have done it over my phone. I know that I did not so why am I still being charged for this and where is cell c security to prevent ?*****. Basically I feel that cell c is robbling me and then saying its my fault. Also I was promised 400mb of data per month by cell c direct on my new contract yet cell c is only providing 200. Again I fell that I have been ******. I asked for the calls to be reviewed to verify my statements...cell c have not as yet done so in over 2 weeks and is still charging me the extra fee and has not responded to my complaints other than to say that I am mistaken. I even asked for the case to be escalated and it seems that this request was ignored. I have been a loyal customer since 2004 and this is the kind of treatment I receive now. Maybe Vodacom will buy out my contract!