How about that. I think the easy way to handle this((becasue you had a hard time getting the orginal hvac co. back, then a gas and go on a two year old system.)VERY POOR SERVICE) Have a different company out to fix the problem then send your bills to the home builder, INCLUDING the gas and go bill. And let the builder deal with the hvac company. In todays market that hvac company needs every builder and homeowner they can get.
Now with that said-- Here in Texas most hvac labor warrentys on new install's are for one year. And a lot of Hvac guys seem to not want to go back on new homes. JUST my experance. The real pros want to make every customer happy, hard to do, but real pros are happy you called.
I just scheduled someone from servicemagic to come and find the leak. Does 150 for the service call to find the leak sound right? fixing is additional but whatever he has to do to find the leak is included. I tried to get a specific method how he will find it but the person on the phone just said he has the tools and decides what to use after he looks over the system.
I hope its good.
I used servicemagic for quite a few projects. Some turned out good some bad. If you found the first guy there I would have not gone back. A good A/C contractor would take care of that without screaming! Thats a little thing called customer service. There are a lot of sites out there and I used a couple of them. I just started using this one called quozzy.com and like it so far. Good luck. Also, you may be able to fix it on your own, not too tough if your handy.