Denied again after appeal - what are my options at this point?

I filed a claim back in November for water damage from a burst pipe. My insurer denied it, said it was "gradual damage" even though the pipe literally burst overnight. I appealed with photos, a plumber's report, everything. Got the denial letter yesterday - second denial. Same reasoning, almost word for word.

I'm honestly at a loss. I've been a customer for 11 years, never filed a claim before. The repairs are going to be around $14,000 and I cant just eat that cost. Has anyone gone through a second appeal or escalated beyond the insurance company? I've seen people mention state insurance commissioners but i dont know if that actually does anything.

Any advice would be really appreciated. I'm starting to feel like the whole system is rigged against policyholders.