How does one get out of timeshare contracts?

I already own World Mark points and a year ago was talked into purchasing more. The downpayment was applied to a credit card, which they issued. This last December I was talked into purchasing another one. They told me they would buy me out of my WM contract. They too put the downpayment on a credit card. In the end, they never bought my WM contract. I now am making four payments a month to cover both credit cards and the timeshare payments. I'm on the verge of bankruptcy. I want to end--get out of both contracts. I want them to repossess what they sold me and I will owe them nothing more. I want someone who will negotiate the ending of both of these contracts.