Need Advise Re: Engine Builder

[agro1]

Here's the story - Motor comes from engine builder and is installed by a reputable shop (HOC).
I ask builder, "How should I treat the motor since it is new ?"
his response, "Drive it like you stole it..."
Rear main won't stop leaking - Motor comes out, back to builder. They fix it and pay for it to be put back in by HOC. No prob.

Right side head gasket blows. Heads come off, and go back to builder. After inspection, nothing wrong with heads. Gasket builder used was a graphite OEM style replacement for a motor running 12:5.1 compression. I paid for and my build sheet says, "Fel-Pro gaskets throughout".
Heads back at HOC to get put back on and engine builder says he will not pay for the head work done by HOC. Builder says the motor was detonating (I run 100 octane only). I said if the motor was detonating the carb wasn't adjusted properly when it came from you and you told me to drive it like I stole it. Builder tells me once it was installed in the car it needed to be "re-tuned under load", which was never done. Builder states they tuned it on the engine stand while running it in, but after it went in the car it needed to be tuned again under load. He said the installer should have known this.

Am I missing something here guys ?? Is this standard practice ?? Should my motor have been tuned again once it went in the car ? I spent close to $12k on this motor alone and would think the builder would stand behind it. The simple fact is an inferior gasket was used and the builder is trying to say because the motor was detonating he will not warranty the work. Mind you - HOC said the motor was NEVER detonating and the build sheet said "Fel-Pro gaskets throughout" and another gasket was used that failed. I do not want pi$$ them off in case there is a problem with the motor down the road, but I also feel as though they are not honoring their warranty. Any thoughts on how to proceed ? Thanks in advance.