Data bundles consistently mixed up

I had a running monthly bundle on my account and I purchased a daily bundle because I knew I would be using a lot of data streaming from YouTube. Then while I'm streaming I get a message that my monthly bundle is depleted. I called 4 times and each agent gave me different instructions. This is not the first time this has happened, I already have a pending case since March which they still have not resolved. So I have effectively lost R110 from a 300mb monthly bundle I didn't get to use and a 1Gig daily bundle that wasn't being deducted. It's absolutely ridiculous and frankly ******** that MTN gets away with such thievery