Advice on shortfall buck-passing please!

vdz

I took out a small endowment mortgage in the 80s (£12500) with National Counties BS, Epsom. The life assurance was with Friends Provident. I don't have any correspondence on file about how I was introduced to taking out a policy with FP. FP are insisting the shortfall is not their problem as they consider NC was my financial advisor. NC fervently deny this, saying they never recommend insurers in this way but gave me an ex gratia payment of £1000 off the capital. The shortfall at the end of the period, 2012, is calculated to be between £4-5000, a hefty percentage of the original amount borrowed. I can't foresee being able to pay off this amount in one go at that time.
Is there any way I can resolve this buck passing? If not, what would be the best way to make sure I make up the shortfall eg by paying more insurance over the next 5 yrs? Could/should I change life assurance provider? Any other ideas? I'd be most grateful.