Yes you can, you have many ways you can go.
First I would start with your agent, he is the one that knows you and you pay your money to. Get he/she involved in your behalf.
Make sure he has the names of all the witnesses, let him go back to claims with it first.
They have to prove the cause was other than what you reported.
In dealing with the claims dept start off working with them. Try and see if they will pay for or split the cost of an independent surveyor for an objective opinion. Remember their independent works for them, not you!!
Keep track of all the people you speak with, what they tell you and times dates for same. You may need it later.
If none of that works file a complaint with the Presidents office at corprate, thats when you will need all the contacts you kept track of.
If you need addl info or help p.m me and I'll call you.
Hope this helps, maybe others can add to this.