Insurance Claim Delays

Having suffered severe damage to my caravan in a hailstorm in June 2012 I am still no nearer getting my caravan repaired and it is now November. 

I have supplied my insurance company with two quotes, one fully costed and one for labour only.  My insurance company like the 2nd quote and have been pursuing rhe repairer for costings for the parts for over 8 weeks.  The repairer say they are waiting for Eldiss Caravans to supply the costs,  If it is taking this long to get prices, can they actually supply the parts..

My caravan is insured New for Old but the insurance assessor say that it can be repaired for less than the insured value - it needs a new roof, whole side, heki roof, roof hatches and one fron window, plus numerous dents on otherside filling.

Can anyone help in how I can move this forward as I feel everyone is blaming everyone else for the delay.

Bearing in mind it is now 5 months since the incident, can I start is to push for a replacement rather than a  repair?