Insurance companies are heavily regulated under MGL c 176D. Among their duties are to promptly evaluate claims and settle claims promptly where liability is reasonably clear. You should contact your insurance company and if unsuccessful, consult an attorney who can assist you with drafting a c 93A demand letter for any violations of the insurance companies duties to you. Best of luck.
The above is NOT legal advice, and is NOT intended to be legal advice. No Attorney-Client relationship is created through the above answer.
Your insurance adjuster has a duty to represent you and defend you against any claims. This includes denying claims that are not your responsibility and fighting over claims where there may be dual liability. In short, they are supposed to defend you against all potential claims both legitimate and deny the ones that you are not responsible for.
You're talking about a presumably large adjustment (almost all real estate is worth into the six figures,) for what is presumably a commercial building, with a tenant.... why are you relying on free Internet advice? Hire an attorney to help you.
Do you want accurate, personalized, legal advice that you can rely on? You will have to hire an attorney, not ask on Avvo. I am not your attorney and am not creating an attorney-client relationship by this post. I am therefore giving only general advice. This advice may not apply to you or your situation; may not take account of all possibilities, and may not match the advice I would give to a client. DO NOT rely on this advice or any other advice on Avvo to make your legal decisions. If you want an answer to a legal question you should retain an attorney who is licensed in your state.