HomeSure of America, Inc. Sears Home Warranty Denial of claim for preventative maintenance on water header Ft Lauderdale Florida

I have Sears Home Warranty that is under HomeSure of AMerica, Inc. in Ft. Lauderdale, FL and pay for the whole home warranty to cover appliances and also water heater, HVAC unit, etc.  My Rinnai water header started leaking so I called them out nad they sent a local contracted tech.  The tech asked if outside maintenace had been performed and I told them no. 

The heatexchanger was bad and subsequently caused the gas valve to be damaged.  The denied the claim due to improper maintenance based on what the local technician told them.  THe manufacturer does not require outside contractors to provide PM and I have city water.  The PM involves flushing the lines and cleaning the water filter.  Both taks 30 seconds to do and I do this annually and document in book. 

I am also a licensed general contractor and does my own maintenace for my own rental properties.  Rinnai even publish on YouTube how to do this maintenance on their own.  I have been without hot water for two weeks and they keep denying the claim without any good reason.  Now I have to take them to small claims court to get my money back.