Mortgage shortfall NRAM refusing to help

Hi,

I really need some advise as i feel like i have no where to turn. I've had a property for sale for over 2 years and finally received an offer for £42500 this week which in my opinion is a light at the end of a long tunnel. Issue is that if this offer was accepted there is a shortfall of £13k. I've spoken to NRAM who are not interested in helping unless i have the capital to cover the shortfall which unfortunately i don't and i have no equity to raise the funds. Family is not an option in terms of borrowing and financial situation means i'm unlikely to get a loan. So i guess the question i'm asking is do i have no way to force the issue with NRAM? I accept my liability to pay the difference and am more than willing to do so but apparently i don't meet the "criteria". The stinger is that if the property was reposessed they are likely to achieve less than the offer and they would chase me to pay the money which i would probably be allowed to pay monthly over a fixed period!! Am i really expecting to much here ??

Any help / advice would be greatly appreciated.