Is it worth claiming compensation for what i believe to be a missold endowment policy?

we were told it was guarenteed to meet its target ( in 2024). after a letter back in 2003 warning us we would have a shortfall if we didnt up our monthly payments by �50 , we decided to switch to a repayment mortgage and surrendered the policy. has anybody had any joy with such a claim? im abit wary of the "no win,no fee" companies , and would just like a bit of advice. thanks....