Need help cancelling a purchasing !!

I have activated a Rain sim card and it's sad to say after the purchasing I realised we had no coverage in my area .I tried to contact Rain Internet Service Provider to cancel/deactivate the sim card because as a student it's really unacceptable to lose R250 each month off your bursary allowances .I tried to reverse payment at the bank aswell and they said I must contact Rain personally ,which I cannot do because there is no support nor contact details .