Again! ***** with Cell c

Today 25 of March, Cell C debited money out my account again, after phoning them to stop it as I am not a client and did not agree upon this debit order. I have complained for the past 3 months and nothing has happened. They say thay my mom gave them my banking details which is not correct as my mom has an account for them and has been paying it for the last 3 years. I am sick of this. Cell C is hard to get hold of, they blame the client for them taking the money out of their account.