Sadly, your situation is something very common, it happened to me 2 years ago, i've spent a lot of money and i was scammed by other companies. I recommend you that if you're going to hire a company to help you with the problem, DO NOT PAY ANYTHING UPFRONT, because it use to be a fraud. I was investigating a lot on internet and i found some interesting articles, maybe this one could help you with your problem:

http://www.timesharescam.com/blog/98-cancel-a-timeshare/

The 90 minute presentation we attended turned out to be between five to six hours. Once we got down to signing the contract we were rushed through to "get us back on vacation." We were told the timeshare we were buying was previously owned and therefore we wouldn't have the right to rescind. Violation of Mexican law.

The sale of our existing timeshare was a condition of purchase at Velas Vallarta. The salesperson misled us about the guarantee to sell our existing timeshare for $60,850. We didn't get the guarantee until we were leaving after signing the contract. The guarantee was for no more than to list the property for sale for $60,850.

We talked about the RCI bonus weeks we were getting. We talked about the cost of $169 or $189 a week. Nothing was said about having to pay maintenance fees first.

We were told we were getting a $80,000 annuity. We then found later it was an "anticipated" annuity.

Just want to add our names to the list of complainants. Our scam goes back to 2003. After a high pressure 7 hour day we finally succumbed to the tactics. Unfortunately, we did not have the sense to get out of there. Two days later we presented our letter of cancellation of the contract. We were moved up the chain to Johnny Noe. He lied to us about not being able to get out, about being able to sell a timeshare and about being able to swap with RCI. Just recently we have seen others get out on the five day cancellation clause. Since the fateful day in 2003 we have only gone there once. Our fees for 2012 are in arrears and Velas is starting to harass us. Does anyone know of a reputable lawyer or government body which will listen to our case? We have been lied to. We want out. We want some of our money back. Canadian suckers.