For your brother, I would tell him to call two places and compare how they talk to him. A good mechanic usually explains things in normal language. If they make you feel stupid or rushed before they even see the car, that is a bad sign. Reviews help, but the phone call tells you a lot.

Star Mechanical Repairs in West Ryde was fine when I used them for a service and pink slip. Nothing dramatic, which is exactly what I want from a mechanic. They found one small issue, explained it clearly, and did not push me to fix three unrelated things on the spot.

I have not used TGM myself, but a workmate in Seven Hills speaks highly of them. What stood out to him was clear pricing before the work started. For me, that is the big thing with mechanics. I do not need the cheapest shop; I need someone who tells me what the bill will look like before the car is already apart.