We where on the month to month contract would MTN

We where on the month to month contract would MTN.we paid R429 for the month and another R429 pro rata leaving out the R150 we paid for sim activation.when we go to the store to cancel they tell us we have to pay a further R429 for the router upon cancellation which we wasn't told when we took the contract.nothing stating in the hard copy contract that we have to pay another R429 upon cancellation.now I am going to lose out R858 because no one explained the terms of this to us.very unhappy customer