Debited twice in one month

I took a contract with mrp mobile in April 2015,I received the tablet around the 20th april and was told my 1st debit order will be on the 28th of may 2015,we agreed on 129 per month but they deducted 226 on the 28th of may and again 99rands on the 29.I called and the consultant told me abt other services which I knw nothing about,rescue box and something else.so I told the consulted that I wanna cancel the contract coz even now they said I have used R 32 already for the month of june which I don't know how coz am not even using their sim card,she said to cancel I have to pay in R 2300 within 30 days.I regret ever taking a contract with MRP mobile its bad service.