Deducted call charges from two cellphone accounts

Autopage deducted calls from my two daughters cell phone accounts, which I pay. Both are on MTN Anytime 100 Topup. On my Desember 2014 invoice, they deducted R86.84 from both cellphone accounts, which were wrong. I went to them in January and asked them to pay it back. It is now September (8 months later), and all I get is promises that the matter is being handled. I call twice a month and visit the store once a month, to see if they have heard anything about the money being paid back. Everytime they tell me they will call me back, but I hear nothing from them.