Being overcharged by multichoice. ***

Iam on compact and on pricelock. My monthly premium is R499 including insurance is R554. But since last month September I have been overcharged. IAn amount of R 715 was debited to my account, on enquiry I was told it was an error it will refunded, but I never got my money back. This month in October an amount of R688 was debited from my account, on enquiry I was told the price lock department will give a call. But to date no one called me and still no refund. Please help me.