Rent to own deals are bad business for both parties involved. No legitimate bank will enter into any kind of rent to own agreement. A banker I know has been in banking for 25 years, and told me to never get involved in rent to own deals on real estate. No legitimate bank wants anything to do with rent to own deals. You buy or you rent. Buying or renting are two totally separate concepts.
I would lose the funds and walk away. Learn from this.