Disappearing data and Airtime

I am furious at MTN and how they constantly ***** from me. I bought 3GB data last week on the 15th of December, today on the 20th it is all gone together with my R100 airtime. I called the call centre and they couldn't give me a proper answer. they told me about the data restrictions and I told them that my data is constantly restricted. this happens whenever I decide to load big data. I have been using MTN for over 10 years and this always happen and they never made an effort to sort it out.

I am now looking for recommendations for better networks.