Get absolutely everything in writing. Verbal agreements count for nothing. Even written refusals of permission to sell count for a lot in court.(posted 8849 days ago)Get written offer on the house naming a price. Write to the lender saying that you will pay the difference between the offer and the debt owed. Get lender's written refusal to allow you to sell.
Get copies of *everything*. If the lender does refuse in writing, hand in the keys and keep your written copies safe.
Any subseqent shortfall claim is likely to be reduced to the difference you had originally offered to pay - provided you keep written proof.
Lee