Double debits

I was double debited in December and January, I then contacted them and asked to be reimbursed but till date this has not been done, now this morning I see they want to debit my account with my monthly fee and anadditional R50. I was not aware of the additional R50. So they think they can debit as they want? I expect to be contacted ASAP before I make effort into taking this up further to a lawyer, I want to be reimbursed and my contract cancelled with immediate effect and at NO COST to me.