MTN Charging for data bundles and does not deliver

Yesterday, I purchased 4 x 1GB MTN data bundles. When checking my balance, it showed, I had 4 GB available. After 3 GB had been used (downloaded + uploaded), I could not browse or download anything. The MTN error screen popped up saying I had insufficient funds. I then checked my balance and it showed I still had 1GB left. I kept trying and it opened up a few pages before throwing the error again. Then I gave up and the data expired. 1 GB of data wasted. Its not fair for MTN to charge you for something and not deliver unless they are doing this intentionally and *****ing from paying customers.