Insurance nightmare: denied claim on a Trane compressor burnout in a humid attic

Hey folks, I'm a 2nd year apprentice trying to wrap my head around this insurance BS for HVAC jobs. We had a Trane XR17 unit in a customer's attic go down last month, compressor totally fried from what looked like low refrigerant and poor superheat management. Filed the claim with our GL policy, but they denied it saying it was 'maintenance negligence' even though we documented everything with gauges and pics. Been in the Houston suburbs my whole apprenticeship, and these hot, humid jobs are killer on equipment, zone 2 stuff you know. Anyone dealt with similar denials on compressor failures? How do you word your service agreements to cover this crap better? Saw a post on r/HVAC about pushing back on insurers, but need real tips. Edit: talked to the boss, might need to add a specific rider for equipment damage.