unhappy with cell c

I had 2 contract phones with cell c, which was ending in September 2018. I called cell c to cancel both contract but only one was cancelled . I followed up on the other one and they said I did not cancel that one, then I asked the lady I was speaking to, to cancel it. she confirmed that it is cancelled but every month cell c takes money in my bank. I went to one of their branches in alberton and also the lady there confirmed that both contract are cancelled. please assist, cell c makes my credit to be bad as I reverse that money every month and reverse charges are ****ing me. what is worse is I always close the code they are using to take money in my account but the following month, they will take more.