Scammed again

Got this warrenty 2 years ago and paid in full.  Now have transmission trouble and they refuse to pay saying that I altered the vehicle with oversized tires.  I purchase the vehicle new in 2005 with 20 mile on it.  It has the exact same tire brand, load range and size it came from the factory with and is recommended on the door.  Never has been altered in any way.  Oh Course, you can not get anyone to talk to about this.  Am now scammed for $2500 for warrenty and $994 for repairs.  Is there any way to keep this company from scamming everyone?  Tim Hobert, Port Charlotte Florida, oakpkwayne@AOL.COM