Data Theft

I use a pay as you go Internet Data Bundle & purchase 2Gb per month, MTN gives me an additional 1Gb Night Time Express as well as 2Gb Promotional Data. Now the rule as you use the Internet they take it off the promotional data first when that depleted they use you 2Gb contractural data. They are not doing this they have taken off my contract first, I have sent numerous emails to them asking them to correct it ASAP with no success at all. The result is now I site with me internet because the contract portion has been used up, although I am sitting with night Express and Promotional Data which I can't use. I now have to purchase a new bundle to get connected, this is theft, you pay upfront and MTN does as they feel. When is this type of service going to be stopped, it's a disgrace. MTN's service is pathetic and they hide behind help desks which are useless.