Have him tell you how he determined that
the rear pads needed to be replaced.
Were they removed and the linings measured
or was it just by looking at them that he
determined that they needed to be replaced?

 

He said he removed them and that they need to be replaced in 3000kms or so.

 

I think the service manager that told you that is full of poop.
The rears should last much longer than where you are currently at, mileage wise.

Simply looking at them gives you a good enough idea as to whether or not they need to be replaced. Not necessary to measure unless you want to split hairs.

 

Hey,

I´ve decided not to change my break pads yet. I agree front pads should be changed first than rear pads.

I will try to see if they look wasted.

 

3000kms translates to how many US miles?
If he went to all the trouble to remove them,
inspect them and put them right back on,
why the hell didnt he just replace them?
If you are a good mechanic, you can tell
if the pads are bad without actually removing
them. Heck, some replacement pads have
'chirpers' that scrape up against the brake disc
when they get too thin and you are about to
get into the rivits.
Thats like tearing down an engine, telling
the owner that the main/rod bearings are going
to go bad in 3000kms, reinstalling the old
bearings for another teardown and bearing
replacement in 3000kms.