Question Author
Hi, thanks all for your answers. After much digging, I have had the answer confirmed.
The procedure I outlined in the question, where it says 'Service Now' is not to display the service interval but to reset it. When I had that on the display, I thought it was telling me it needed one now, but it is in fact telling you to service the car as you have just reset the indicator.
Holding the trip reset for 2 secs with the ign. off shows how many miles or days you have left.
Thanks all for your help.