CANNOT LOAD DATA

I currently have four contracts (all Top up) with MTN. <br> On my main contract, I added 1G data that is loaded every month.<br> From time to time, when the data is depleted, I just call the call centre, and load another 1G once-off data.<br> I've been trying to load another 1G data since Monday 07.03.2016, with no success... After a lot of frustration, I was told the reason is a usage limit on my account. As per my knowledge, when you have a Top Up contract, you get an x amount airtime and data per month (as per contract) When depleted, you either go without or load new data / airtime. I requested the usage limit to be removed, and a few days later, is still in process?<br> I am really frustrated, as I need more data, and the response I keep getting from the call centre agents (when I am lucky enough to get hold of one) is to call back in a few hours as the system is processing. When and how was it all changed? And how can it be resolved? Without fueling my frustration levels even more?