Deducting without any services offered

Worst ISP I have come across. I ordered a 20gb package including router but when the courier arrived there was no router present in the package. I then send it back and phoned customer care to cancell my package. The lady over the phone said everything is sorted and cancelled but yet now for the second month they have tried to deduct +- R500 from my account for no serives offered or products used. MAKE THIS STOP. I HAVE CONTACTED THEM ON NUMEROUS OCCASIONS BUT THIS IS STILL HAPPENING!!!!