good approach. both mehran and hamza younis deal in orignal toyota parts. both shops are 1S and are infront of each other in saddar rwp.
usually automatic car brake pads are recommended for inspection at 40k kms interval and replacement accordingly. you can check the table in your manual.
its a very good decision to opt for orignal parts.
if you look at my thread you can see similar details regarding brake disc pads. i got bendix brake discs and they have a marking on them for replacement.
also there is a metal blade like cut metal attached to brake discs which makes noise upon braking once brake discs wear out.
i believe u r paying quite alot extra for sticking with 3S and 1S dealership however its good for the car and peace of mind as well.
good going.
you can always get in touch if any help or guidance or discussion is needed.