Can't Stop Brake Noice...Help

I purchase a 2001 Galant ES about a year ago. After 6 months The brakes started to squeal when I pressed the brakes. I have had a brake job done, but it continued the noise. Also, I changed the rotors out for cross-drilled rotors and still continued to make the noise. Just recently I brought it to Fire Stone and they cleaned out the drums, but it still makes that annoying sound. Every mechanic that looks at it has no idea what it is. Can someone please help!!!

Hi, have you tried the pads? Are they genuine ones? I would go for a good inspection of the retaining clips as well. Try having a look at the back plates for any damage or not sitting properly.

Hi, have you tried the pads? Are they genuine ones? I would go for a good inspection of the retaining clips as well. Try having a look at the back plates for any damage or not sitting properly.
check the shims behind the pads lube the rear surface with a little grease the shin and the piston face also check the sliders are free and not loose in the bushings