All i want is them to stop the debit orders and to cancelle the contract

I took out A contract at mondo mobile ,the consultants that help me **** about the whole internet package and i thought it is too good to be true.The day off arrival i found out that the package is not a 300meg line for R399 but a10meg line. After arrival found out its a 10meg line and took it back to a mtn store. I was told that it will be send back and that the contract will be cancelled,but now mtn/mondo mobile is debiting me R3600 every month and when you phone they drop down the phone or let you stay on hold for hours, can you please help very bad service from mtn / Mondo and concultans that lei to you to make sales very unhappy