Mine used some kind of metal clips and silicone. Did they not use the clips too?

Wrong! Completely and utterly wrong to do that. Withhold payment and tell the contractor to come back and fix per manufacturer instructions or you will not be paying him a dime. I'll be surprised if your plumber is willing to do the hookup with the sink looking like that. Best of luck to you getting it fixed, there are some folks on here that will likely give you good advice on what to say to the sink installer.

Isn't that silver piece in front a sink undermounter bracket?

clt3, The silver piece in front is a cabinet support bracket. We installed IKEA cabinets and that is the cabinet piece. It's not supporting the sink in any way.

Do not put anything in that sink until it is mounted properly it came with instructions for mounting and since the istaller decided they knew better they can wait for their money until it is fixed. No plumber i know will touch that with a 10’ pole.

Oh, Joe (Joseph Corlett, LLC)...........................................

They have a metal support in the front and they probably have clips in the back and a few on the sides there is plenty of room. I think they used that as a temporary support they just never removed it.

That said, I would be more pissed about the way that hole is cut around the pipe, if they would cut the entire backside of the cabinet it would look cleaner and better than that cutout around the drain pipe.

I just don't get this installers, why it is so hard to drill one hole instead of hacking up the back of it like that at least make a straight, neat cut... It look horrible even being this under the sink.

Well it definitely needs to be strapped up. They can't think the installation is complete. Its going to break the quartz like this. Before a plumber comes in someone needs to take care of that. Whose job is that?

bumping this in case Joe is around.

I think you need to stick your head (and camera) under there a bit farther and see if they used any screw/clips around the peripheral.

Since you changed from a double sink to a single, it would have been nice if the plumber had come in first and roughed in the drain. Now you've got 2 to deal with instead of one.

"@millworkman I'm picturing that scene in It's A Wonderful Life when Clarence and George are at the bar and get into trouble....."Oh Jo-seph!!"

This is hysterical. And so true.

Back those brackets out, drop the sink, scrape the silicone off the flange (if they used any) and the bottom of the top. Secure a Hercules Universal Sink Harness (Braxton Bragg) or a couple of Sink Straps from Regent Stone Products to the cabinet sides. Silicone the sink flange, run a pipe clamp through a hole in a 2x4 that spans the top and through the drain, snug the sink, and check the reveals. Tighten the HUSH/Straps, pull the clamp, clean up the silicone and your sink is mounted permanently and professionally. Like this, please.

While the sink is out, re-drill the hole for the dishwasher drain to the top of the cabinet, please. It's much too low now.

I am not a fan of sink clips, manufacturer supplied/specified or not. I see this constantly:

Since they take up so much room, they make the front top rail fat. To keep the front rail skinny, fabricators just eliminate the clips from where they're the most needed. Skinny as you please with a strap.

Joseph Corlett, thank you! The countertop guy is coming back out today...in fact I'm waiting for him now. I like the harness option much better than the clips but I think all this guy is bringing out is clips. I had a difficult time even getting them to agree to come back out.

Plumber will be coming tomorrow so I'll tell him about DW drain.

I know ideally, it would have been better to move the plumbing drains from 2 to 1 before this ginormous sink went in but it just didn't happen.

Thanks everyone for the comments and suggestions.