I'm being debited for a contract that expired!!!

My contract expired and is running from month to month. I'm on straight up 100 top up. As from what I have read I'm only supposed to be paying R100. However I was debited way more and upon asking them to rectify this I was told I'm paying for possession of the phone incl the top up?! I would Iove to see where this is stipulated in the terms and conditions that I was referred to. I would not recommend anyone to get a contract with Cell C. If this is how they operate. I can understand if something makes sense however this is plain *******. The money debited is equivalent to a phone I did not even upgrade on. If they can highlight where it states in the terms and conditions that you will pay \for possession of a paid up phone"as well as the straight up 100 I would gladly understand. """