I had USAA insurance for over 17 years and never had a problem. 2 Years ago, they started getting petty on me and refused to pay a comprehensive claim on my van stating there was no proof on m problem that it was , in affect, a manufacturer defect. Bottom line, it was the result of my wife running over a curb and bending the rear axle brace slightly causing the van to be out of alignment. Total cost was for 1300, and I had a 500 dollar deductible.
This went on for 2 months with my van in the shop and me discussing with USAA claiming they should pay. They then came back and flat out refused and and when I asked for scientific eventide that it was a manufactures defect, they said they were not obligated to give it that their opinion is sufficient.
The above is my incident with USAA and trying to get them to pay a claim. What I did follows even though this is slightly different then your claim...
I filed a small claim lawsuit against them in court for the cost of the damage, as well as the lost time of my van based on the cost of a comparable van. I didn't even hire an attorney...but maybe should have?
Within two weeks of filing the small claims suit,(BTW which was for 4000.00 dollars), they agreed to settle out of court for (3000.00 dollars which I took).
Not sure if you have checked this avenue yet? Please note, I am not an attorney, but I felt my rights were violated by my insurance company because as I read it, unless they have overwhelming proof that it was a manufacturer defect and not cause by my wife running over a curb, they are oligated to pay it. This is why I pay an insurance premium every month.
Thus, I think they should be paying you in your circumstance, and are just playing games with you. I would go after them in court, and recommend getting an attorney.
I have since canceled my insurance with them!!