Any Cadillac owners tried that Sharjah garage claiming to be experts? Need real feedback

I’ve been putting off fixing a rough idle on my 2013 CTS for months because every mechanic I talk to either wants to replace all six coils at once or just clears the codes and hopes for the best. Someone at the petrol station near Al Khan recommended a place that supposedly knows American V6s really well, and when I looked them up I saw they market themselves as an Expert Cadillac Repair Service Sharjah which sounds promising on paper, but I’ve been burned before by shops that talk big and then deliver nothing. Does anyone here have firsthand experience with them, good or bad? I don’t expect dealer-level perfection but I just want someone who can properly diagnose a misfire without guessing or charging me for hours of “checking.” Also curious if they actually have the right scan tool for the GM computers or if they’re using a generic OBD reader like every other small garage. I’m in Sharjah Industrial Area pretty often so location is fine, just want honest opinions before I hand over my keys. Thanks in advance.