Vodacom bunch of *******

I have a contract with vodacom which comprises of a number of sim cards from data to top up minutes, one of my sim card contract came to an end and since I had no use for it I decided to cancel it but to this day they refuse to cancel it, it expired last September and to date they are still charging me month to month charges on that sim card. I have called them numerous times to have it canceled but they keep promising me it it will be canceled but they never do. They are ******* and I'm waiting for my other contract to expire and I won't use vodacom again. I used to love the network provider but I even when they send me their messages I wish I could block them but unfortunately I don't have that option.