Unhappy with Service and becoming way too costly

Been with MTN for the past 8 years and it was always affordable. For the past 2-3 months it has become really costly and I can't afford to be on the network anymore. I'm on a top up contract, and usually top up towards the end, I'm finding myself recharging R5 at least once a day to stay on the network, 12/04/16 I had to recharge more than 4 times in 1 day. The 19th had to recharge 3 times . R5 is not expensive, but recharging R5 a day and more then once in a day its too much and add ups. All the updates, including my software update is set up for wifi environment only, and if I update its only within a wifi enviro. I checked if I was subscribed to anything and im not. The call centre agent said the system cannot say if the updates were done within a Wifi environment so how can they use that as an excuse??? I sent an email on the mtn website received no response, I called 2 times, before the 12th in which they gave me references numbers but received no feedback. So I called about 10 times on the 12th. I'm highly frustrated with the service and don't think its fair to get service like this, wanted to get a solution but feel like they can just take there phone and contract!!!!!!