DSTV #*******

I am once again disgusted at DSTV. This is going to be the cause of my mother cancelling her subscription. Each month they deduct a different amount from her account via debit order. When you call them they say they fix it and then back to the different amounts they debit from her account. Surely this shouldn't be that difficult? Please can someone assist my mother in this regard or else we have to cancel the subscription!