Total Protect Home Warranty review: I would like the warranty company to honor my contract and pay $12,989.65 less the $500.00 max out of pocket for 12 months

My policy covers HVAC system. They gave me approval to go with my own contractor. My unit was 26 years old. Very rusted and had holes in drain pain which leaked and destroyed unit. My contractor called the manufacturer and was told the unit was obsolete and parts were no longer available. So, my contractor gave an estimate for a comparable unit and it was installed. Now the warranty company says they will only cover $1,141.40 out of$12,989.65 because they think it could have been fixed even though the manufacturer said it was obsolete. I don't know what to do. I don't have that kind of money. I am 71 years old and on a limited income. I have over 66 emails in communication between the warranty company and my contractor, who by the way was very conscientious about giving the warranty company Avery bit the information that was requested.
Thank you,

Lori M. Jensen

email is [protected]@charter.net

phone # [protected]