15kms is a major service. Services should be every 7500km's with alternating minor and major. Minor is just the usual oil, filters etc and the major is valve clearances and a few other things as well. Do a search as there has been quite a bit of talk about this but to answer your question it should be a major service so I suspect it will be quite expensive i.e. a few hundred euros at least I would have thought.
Check your service history if the bike is new to you as I just bought one that has the servicing the wrong way round i.e. the 7500km service was carried out including the valve clearance etc so my 15kms Im just getting a minor.