RAIN not taking care of their customers

My sister is illiterate so I assisted her in taking out rain. We discovered that there is no proper coverage in her area it has been 7 days since she requested a call back no one from RAIN has called her. Instead when I help her to cancel the Simcards RAIN still wants to debit her account though she didn't even use their data. The debit order is due in 3weeks time. I need your help in stopping it before she is charged for nothing