Your story is all too familiar! We experienced the same sales scam. Your first step is to google PROFECO. They are a Mexican gov't office that handles all these timeshare scams. Then contact your nearest Mexican embassy and tell them how this hotel has left a bad taste of the country in your mouth and will never go back or recommend anyone to visit. Insist that they contact the hotel and help you cancel your contract. Continue to email/write the hotel detailing all avenues you plan on pursuing...even though they don't respond. It is appalling how the Mexican gov't can allow these scams to happen in their beautiful country. Instead of a memorable experience with desires to return, we have made it appoint to never go back!
GOOD LUCK!! It happens to the best of us!