You needed to ask this question two years and one day ago.
What ever the tactics are, you are committed to them ...now.
You indicated this owner has financed some of your neighbors also. This MIGHT be your lucky day.
But you will need to do your homework.
Read my Trulia blog titled something like "Rent to own, are they real?"
Based on the 'eight-ball' the lender is now behind, you may find yourself in the drivers seat.
Time to take your finding to an attorney.
What we are talking about here is the Dobbs - Franks Consumer Protection Act.
Best of success to you.