Vodafone — Refund of amount deducted against caller tunes

Automatically there was deduction of balance from main a/c for caller tune activation. For which I called up the customer care and informed that it has been deducted without even m subscribing for it. They confirmed that this would no take place again. Few months later again same issue raised and I informed the customer care about the deduction & refund the amount. This happened again and still they didn't refund the amount to my account. With this my account became zero. So fearing of the deduction I stopped charging the card. Now the deduction still happens automatically but as I don' maintain balance the same doesn't get deducted. Now I have problem has come to my another no. where the deduction happened and they have not refunded the amount . I am in fear that this would happen again and the customer care would just give some reasons and my balance would go off.