As I cover a lot of miles and now change the oil, oil filter, air filter and cabin filter myself I need to reset the warning light. Though I will take it in when the tappets or plugs need changing.
1) Turn the ignition to the ON position, where the dash lights all light up, but do not start the car.
2) Pressing the Sel/Reset (Select/Reset) button and cycle through the display until you get to your warning.
3) Now press and hold the Sel/Reset for about 10 seconds until the display changes to a recycle/restart maintenance symbol and a return/exit symbol (that's how I call them) is displayed.
4) Now press the 'i' (Information) button which should highlight the upper 'circle round a spanner' symbol, then now press and hold the Sel/Reset button until the display changes to and new service mileage setting. You may need to do this twice until you get a required 12000 mile figure (mine actually displays 12400 miles after a lower number.
I hope I described it okay, I went out to the car and tried it out. There were other symbols too, spanner pointed to by spanner, '7' , 120 followed by a sun/star. Do you think the '7' shows how many services or resets?