don't lean on it?? wth? do not pay them. those flimsy metal brackets are rated for, what, 25 lbs?? maybe? this is just a 'no'. throw a fit and get your new cabinet. IF they cut it more than necessary, why wasn't this addressed at the time?

Totally unacceptable...in so many ways.

I can't even imagine somebody installed that like that and actually had the brackets with them showing they must do this often?

Shelf brackets with sheet rock screws into MDF or particle board. What can go wrong? Wha i the back 3/8 thick?

DONT PAY THEM AND START FRESH.

At the very least build a wood support frame holding up the sink but that would be at last resort.

Im hoping there is more to this then we are seeing?

3/4" granite needs a minimum 5/8" plywood underlayment for support, "no MDF and no particleboard. This method is mostly used on the West Coast. On the East Coast, 1 1/4" is common and is considered strong enough to not require an underlayment and is not used. Underlayment also gets used depending on the edging.

Take a look at the thickness of the granite and report back.

Firstly, the sink is too large for the cabinet, which does not appear to be a proper sink base. Granite requires rough tops. Why do granite without putting an edge on it? Bad design, improper materials, a hack job from the ground up. You need to replace the cabinet, install a smaller sink, then do rough tops and proper fabrication and installation.

The pictured wood-shim-and-polyester-over-the-flange method of supporting a sink is a guaranteed failure without additional support. I'm not crazy about the shelf brackets. I'd be a toughie, but you could still get a Hercules Universal Sink Harness (Braxton Bragg) or a Sink Strap (Regent Stone Products) to support the sink. If you did, you could stand in the sink without repairing/replacing the cabinet.

The front rail on frameless cabinets is nearly only decorative in nature; it functions as a doorstop and as a stretcher to keep the cabinet sides apart when the HUSH or Sink Strap try to pull them together. I wouldn't worry about it. When you strap the sink in place, you've turned the sink into a 9" deep stainless steel truss which supports the stone better than any melamine.

I'd make sure they applied a generous bead of silicone between the sink flange and the granite bottom. See if you can slip a thin knife between them, please. A topical bead is useless.

If they can't/won't do a strap, angled aluminum can be fastened below the cut melamine to support the stone:

"3/4" granite needs a minimum 5/8" plywood underlayment for support, "no MDF and no particleboard."

5/8" plywood on the flat has virtually no strength in tension, especially in this application it's useless.