Angry with Cell C airtime continuously disappearing

I bought R235 airtime yesterday, I wanted to activate the all network minutes. Over R100 airtime disappeared when I phoned customer service I was told that I subscribed to something which I never did. This is not the first time I experience this nonsense from cell c, I was told this have been blocked but no I think this is Cell C way of making profit. I had to recharge again. I'm very disappointed with Cell C I'm even thinking porting out.