Got to reset it yourself mate,
Ignition off
turn the clock adjuster knob clockwise and hold it
Ignition on (still holding clock adjuster)
Press the trip meter reset button
Let go of clock adjuster
(if the service warning still shows press the trip reset again now)
And that should be it

It's a bit tricky getting your hands in the right place the first time you do it, but you don't need to be double-jointed fortunately.
Chris.