For a small displacement bike like the R125, 180€ is really reasonable at the dealer. You've got the air filter, brake pads and fluids included, so it's a full service, not just oil and filter. At a Yamaha dealership you're paying for the brand and the guarantee that everything's done to spec, so the price reflects that.
After that, if you really want to shop around, an independent garage could do it cheaper, maybe 120-150€ or so. But honestly with 15,000 km on a 2015 bike, your bike isn't worn out so the brake pads should still be fine. Just ask the guy whether he's actually replacing the pads or if it's just an inspection, because that would make a difference.