Cancelation impossible

I have been struggling for 6 months to cancel a fibre line that I have with vodacom. Had numerous phone calls with the customer care and was told that it is cancelled and I would receive a credit. After that my account was debited again and I received no credit. No one at the customer care has a clue what is wrong or what to do. I have since imigrated to The netherlands and it is impossible to get any way of sorting this issue out from abroad