How to reset service message on display screen?

1. Insert key, switch to postion 1, mileage counter has to be displayed. 2. Press left arrow on right side of steering wheel, until TRIP option is highlighted. 3. Press and hold the phone button within 1 second press OK and hold both for 5 seconds. THE shop MENU is displayed. 4. Press down arrow till :Assyst Plus" is highlighted and confirm with ok button. You should see "service data and Full Service displayed. 5. Press down arrow till "full service " is highlighted. Press Ok to confirm. 6. Press down arrow till "Conf. Full Service" is highlighted, confirm with OK button. Display shows Service carried out? 7. Press down arrow to select YES. Confirm with OK button. "cannot be undone" displays. 8. Press down arrow until "confirm" is highlighted. Confirm by pressing OK. Display should say Full service carried out. 9 Confirm by pressing OK

I have on display A 115 need service, what this?

quantité d'huile a moteur pour Mercedes glk 2013

That means you have 115km/mil due for Service A