2003 Envoy Brakes Squeal When Applied

The brakes on my 2003 Envoy XL were just replaced at the dealership. They squeal when the brakes are applied. They have taken them apart three times but they still squeal (high pitched metal on metal sound). I have used this dealership for many years and neither I nor they have had this problem. Any ideas that I might pass on to them?

If they put all the proper anti-squeal grease where they are suppose to, then I would suspect cheapy pads.

Thanks! They say they are genuine GMC parts but I will check again... Appreciate your help!