Mortgage selling property behind in payments

I am 11 months behind in mortgage payments on a rental property and have done several things to keep the property. I did a title search, a certified forensic loan audit, validation of debt letter as well as a qwr via a validation of debt letter to the CEO. They have backed off and doesn't call anymore. At this point I am trying to sell the property and have a possible buyer. My question is should I contact them to request a loan pay-off, should I try to file for a quiet title, negotiate with them? What do you think. I am skeptical about requesting a loan payoff because I don't think they would be honest. The statement shows approximately $66,500 with late fees around $10,000. Therefore at closing I am expecting the payoff to be no more than $80,000 which is ok as I am trying to sell for $115000 which the buyer may accept. However, I don't want to get to closing and see an astronomical payoff. I don't trust them