Just done a quick Google for resetting the service counter on a Golf (as I've just bought one!).
This is for a Mk V. Don't know if it's the same for a Mk Vl:
"To reset the message displays, turn the ignition switch on. Press and hold the odometer reset button "A" located below the speedometer. Turn off the ignition while holding the button. "OEL" will display on the indicator. Press and hold the lower digital clock reset button "B" until five dashes appear in the display. If needed, press the odometer reset button until "IN
01" appears and then press the clock reset button until five dashes appear. If needed, press the odometer reset button until "IN 02" is displayed and then press the clock reset button until five dashes appear.To exit reset mode, turn the ignition switch on and when "IN 01" appears, turn the ignition switch off.
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