Irritated to the CORE!!!

We took a Ipad contract with Autopage in February (should have just stayed with MTN), we asked if we can please have a top up contract that if our data ran out we can buy extra, nope we had to wait 6mths according to the agent. confirmed that my contract is just for R400. first debit order was R600 to our surprise.... to my horror our second bill came, R2297.46. HOW THE HECK IS THIS POSSIBLE!!!!! I signed up for R400, was approved on my affordability for R400, now suddenly I need to pay R2300???? For a Ipad???? I can buy one cash in three months time going at this rate. I have lodged a complaint on their facebook, promised a call, but nothing!!! Who do you talk to? The man in the moon maybe??? I am just so tired of having to fight, I want my account fixed and set straight. I can't be paying this much for data usage.