Incorrect Billing of Prepaid Account

I am very dissatisfied with the MTN customer support. I noticed that yesterday, I was billed for data on my airtime balance, instead of my data bundle, so this morning, when I checked my balance, I have no airtime, but I still have data. I only sent one sms yesterday, and didnt make any phonecalls so that doesn't make any sense. MTN customer support refuses to correct my billing and refund the balance. They are making it my problem that their system gets "confused" if you do not close your apps. This is not my problem MTN, it is not up to me to make sure your system isn't confused and make sure it is billing me properly, you need to fix your system and make sure billing is correct! This is absolutely outrageous that you insist on ripping me off. I am seriously considering moving to another service provider! Call Reference: ***6 * You should notice that, that isn't the only time I called in today.