Claim dispute with Cornerstone Projects

My vehichle was damaged by material from a construction project which Cornerstone Projects is facilitating and was brougt to their attention the incident,extent of damage and i was asked by the Co Director and Project manager to submit a quote and evaluation which i had done and today i am being told that this out their insurance spec as this damage was done by natire and they cant ve held liable. Firstly,if the boards on the project site where that they were working was securely fitted the damage to my vehichle would never have occured. Im now told to get a letter of demand or lawyer to substantiate my claim.

Why ask me to do and submit a quote now refuse to accept ownership of failure to ensure the boards where tighthly secured and make me responsble for the damage ro my vehichle?

I have been parking on this exact spot for tears and never had i encured any damages before only this very time.