debited after paying off account

I concluded my account in March 2015, and overpaid by R800 odd and my account was still debited by Vodacom <br> after i was given a letter to confirm that my account had been settled and prior to that had asked Vodacom to remove my banking details off their system as i would be making cash payment <br> <br> if vodacom can pay back the funds due to me - that would be swell