We have a protection plan for our furnace with TH Oliver. The plan contract clearly states that all diagnostics are covered. when our furnace stopped working we called TH Oliver. The service person diagnosed our problem (incorrectly, we later discovered.) He then stated that since our problem was not related to a malfunctioning part, he would have to bill us for $180! The serviceman himself could not find a statement in the contract to justify the billing as our contract (and the company website http://tholiver.com/service.html) clearly states all diagnostic fees are covered. TH Oliver ripped us off, we paid $180 for nothing as our furnace still does not work! Quite frankly, they are a bunch of crooks!