Home warranty company and plumber having dispute - I get the bill

Background - bought a home in July, and noticed ever increasing utility bills. My home warranty company contracted a plumber to look at my water heater. Plumber determines water heater is fine, but suspects a slab leak for which he needs to come back with diagnostic equipment.

Comes back, feels around on the floor to roughly determine the location, but diagnostic equipment isn't working. Tells my wife that he'll need to return with the equipment, but that he will probably need to jackhammer my floor to repair. I do a little research and determine that it may be better to plug and reroute through the attic.

At this point I have spoken with my warranty company again who says they will cover up to $500 for aggregate repair of the leak; diagnostic costs covered seperately.

Plumber calls me the following week saying he is ready to open up my floor, and will not agree to another method of repair.

I contact my insurance company bc I know jack hammering the floor could get extremely expensive. They won't agree to give me a quote until the floor is opened.

Home warranty company says they will cash me out for the $500 to have another plumber fix the repair. The second plumber comes out and reroutes the pipes for $970.

Now the original plumber says that the warranty company is refusing to pay him for the second day he was out there. He is also trying to charge me for talking on the phone with me and my insurance company on the day he tried to come out. Total bill ~$500.

After talking with the warranty company he should not be charging me because they contracted him, and that he was paid the agreed upon rate for the diagnostics. They told me to disregard any bills he sends me.

I am just worried he could try and put a lean on my house/send collections after me. Can I really just tell him to stuff it?