It goes along these lines: switch ignition on; press the button at the end of the stalk until the spanner and mileage to the next service are showing on the display. Press and hold the trip meter button until the display flashes the correct mileage to the next service. (Could be 6 flashes) Release the button and the new interval will be displayed. Switch off ignition. Use a 5p to hold down the trip meter button. You can go round the flashing cycle again if you don't quite get it right at the fiirst attempt.