Holding fulnerable people hostage with airtime contracts

I am trying to cancel an airtime contract sold by Foschini to my 83 year old mother And have her old number returned to her as a prepaid number as it was previously. Foschini indicated that we must call them a month after the request and they will deal with the change to prepaid. That we did and it would have taken 24 to 48 hrs, but 2 weeks later and they just keep on telling there is a delay with MTN. I get the distinct feeling that it is a frustration tactic to have people not cancelling the contracts.