Cell C allowing sms subscriptions to run off account

I upgraded my cell c contract on the 04/12/2018. I was advised accordingly that I would be billed for pro rata billing. I upgraded and received my new bill but to my surprise my bill was higher than expected. I went into my nearest cell store and was advised that I had subscribed to some content. I would not subscribe to any content esp not content that is being charged at R7 a day. Furthermore I have a limit on my contract and cannot understand how Cell C does not have a system in place for things like this. Cell is allowing third party to access your account basically, surely Cell C then get a percentage of this by supposedly saying that I had subscribed to this content. I have had to pay for this subscription last month and this month again as I went into cell C again to query my bill being over the normal again and was advised that they bill in arrears. I cannot under standard this and would urgently request a response and a way forward to be credited for this amount that has wrongfully being debited from my account.