Debited more into my account

I received a call from one of the consultant from Mobius was told these a promotion for the WiFi rotter for R99.00 per month for 24 Months. The consultant he had explained and I was happy with the service as I noted that I will be saving R60.00 instead of buying data for R160.00 rather take the 3G rotter and safe. So I had agree and went ahead to place an order and I was told that the 1st debit order will take place on the 25th of Feb 2016 as I get paid on that date. So a month late which is this month of March 2016 I got a debit order from Mobius they took R830.45 and hot-spotter R49.00 for what I do not understand. So as unhappy customer what do I do about this cause I never agreed for that much amount if I knew it would have been that much I wouldn't have agreed from the 1st place so I prefer not to continue with this and cancel as I am not happy at all. This is unacceptable at all.