NO RESPONSE THEY LIE

I have previously (friday) put a complaint in, VODACOM rep**** here on hello peter and said they will contact me i am still waiting so im still not happy. They are billing me and debiting my account even though i cancelled this in OCTOBER 2015. I already phoned again in NOVEMBER and she re-assured me that its now canceled and they will pay back my money, i now received another letter saying my debit order didnt go of ! YES i cancelled my contract. What can i do to sort this account out they owe me not me them!!!!!!