Cell c is busy debiting my account without my knowledge or consent

I had a 2 year pinnacle contract with Cell C which was really great and as time went I realised I've been paying for two sim cards as the usual cell c ***** for which no one ever gets a refund for, managed to close the ********** sim and early last year my contract ended, I've been looking into getting another contract lately and to my shock Cell C has "predicted" that and they have been debiting my account since November for reasons I have no knowledge of, I've been advised to sue the company either way I just want it to stop. No one ever takes responsibility for these things, please help!!!