I'd agree with everyone that using a claim company sticks everyones insurance up, BUT you have to do what is right for you in the end, because..

All the recent accidents that my friends and family have had, which have been most probably the other parties fault, have always been settled without dispute by the insurance company as 50:50 costs (used to be knock for knock but now done differently). It is in all insurance companies interests not to fight with other insurance companies - hence they don't bother looking into it, agree it as 50:50, then both parties lose there NCB and excess, and the insurance co's don't have any legal fees to pay out... and you are left pissing and moaning to their call centre geek that it was not your fault!

Hence, if you don't want to use the claim company cos of the overall morals, then.. Ring the other parties insurance co direct and don't claim through yours; Threaten them with you using the claims company and they should prick up their ears and listen. As long as the other party admitts fault, you won't have a problem and you don't get hammered on your excess or risk your ncb if your insurance company do a deal as above on your behalf! I have done this before and it does work ok.