Packet Switched Data Calls - MTN Con

I took out a contract for an iPad with 300mb data, I specifically chose the more expensive option because I'd learnt the hard way that MTN doesn't specifically tell you the line is open unless you request it to be closed. Because of this I have another contract that I have to monitor like a hawk so that my account doesn't over run by a few thousand rand. <br> <br> I was horrified to find out that even though I specifically requested a closed line and specifically chose the more expensive option to ensure this, I have now been billed R800 more for this line, because of an automatic update. I was over charged last month as well, but I didn't realise this because of other open line. <br> <br> It is completely out of control and impossible to monitor, it's costing me hundreds if not thousands of rands each month and no one at the MTN branches can help me without calling 808, it's ridiculous and I'm sick of paying for poor service and getting ********** and conned at the same time. Vodacom at least give you the option to soft lock a line, but no such like with money hungry MTN. <br> <br> I also discovered that my one phone number which is closed, for some reason also is able to over run the top up balance?