Charging for airtime which I don't even know of!!

I have had an account with edgars for some time now. I get my statement via email every month, but I almost never look through it. But recently I did and noticed that I am being charged a amount for a cell c airtime subscription. I don't even use cell c, I have never used them. I went in to see edgars about this, they phoned and said I will be contacted, they never did. Went in again and spoke to a manager, she took my details again and promised to phone me, she also never did. While I was there they picked up that I have been charged that amount since last year july. No body can give me a answer yet and even tell me if I am going to be payed back all that money. I also heard that some other customers has complained about airtime being charged to their account. So basicly they just put a subscription for airtime to be deducted from my account, a cell c subscription which I have never used in any case. So I think it is really bad service for a company to just randomly put such subscriptions on someones account for something that is not even relevent to them and then even worse, is them resolving this matter now! Bad service from a company which iv supported for years!