Yeah correct right now I'm left with 7 months or 9000km for my next service I will see which come first.
No. If you do 15000km and take it for a service, then it starts again. Say you service it on 1 September 2017. Then it is due for service again, either on 1 September 2018, or after 15000km, whichever comes first. Then it starts again from the date of THAT service. So you always service, add 15000km to the mileage and 1 year to the date, and thats when its due.