Vodacom bad service

For the past 5 months I have been struggling to cansel my contact that has expired a while ago. For the past 5 months I have been calling vodacom to cansel my contact without any success. When the contract ended they just cept on billing me and still after calling them for the past 5 months nothing has been done to cancel my subscription. This is totally unexpectebill. Seems like it's going to take me a nother 5 months to get the subscription canseld