MTN's sickening service

MTN is by far the worst service provider, I have a top-up contract with MTN which was taken out for my daughter who went to Ghana for 10 weeks. Before she left to Ghana an MTN Westgate mall consultant (Mpho) to load her phone with enough airtime and data before boarding, which she did but to our surprise when she returned her phone had run a R30,000 bill. From my understanding because it is top up, once her airtime is finished, its finished, she has to recharge. I have been to MTN several times but they keep taking me from one person to another. I went to the head office where they explained to me that I'm on minute top up and once you leave the country it bills like an open line but no one explained this to me, instead I did exactly what the consultant at westgate told me to do. I showed them proof but they keep sending me to the store. I've been there almost 3 times now and Mpho is on leave for a month and whenever I go, the manager is not in. I have had it with MTN, I cant even escalate this problem without the manager. I don't have R30,000, my daughter is still an intern, just today I was told the insurance for my phones have been cancelled. I hope this time MTN you will act!