Hi Ben,
I apologize for the lack of responses, normally we are very quick to respond with numerous opinions and options for help, and we take great pride in this on NICO forums. Unfortunately sometimes we let one slip through the cracks.....
Normally I would expect the front to wear out a little quicker than the rear, but the front pads are thicker when new so often they are due to be replaced at almost the same time. My recommendation would be to get the exact measurements on the pads and compare to these specs so you can judge exactly the difference in wear.
New pads: 11mm front and 8.5mm rear.
The minimum wear thickness: 2mm front and 1.5mm rear.
It may be that your front pads are close to the wear limit too and your service guys are trying to help you get a few more thousand miles out of them but in reality they may be very close to needing replacement too. Often it's more convenient and economical to replace pads on all 4 wheels at once even if they aren't all completely worn out. I'm just guessing here, I could be wrong, that's why I'd suggest getting the measurements on all your pads to know for sure what's happening.
Also there are 3 existing threads discussing brake replacement and maintenance with really good info, you can access all three threads from here:
post6077149.html?hilit=brakes#p6077149
I'm sure we'll get some more discussion on your specific question as well.