Misleading sales approach

I got a call form Bongani at Vodacom direct in December 2012 telling me that since i have been recharging a lot , i have won myself a phone and i will only paying for the airtime for the amount of R100. They didn't tell me that it is an open line contract were i will be building my own bill. I actually ended up getting 4 phones and 1 simonly were in all of them they told me that i have won them as i have been recharging a lot and it was a 12 months contract, Then when 12 months is over they told me that my account is in errars as i didn't pay my account , then i was told they were all 24 months contract , to my shock. Now i am unemployed i cannot afford to pay all of the amount due and they took my contract to pre-legal .all i want from Vodacom is for them to cancel my contract with no pay on it and to deactivate all my numbers and call to make payment arrangement with them on the remaining amount that is only for 12 months contract not 24 months.