Is there any way of checking without using VAGcom ie via the highline or such whether a car is set to longlife or t&d?
You don't actually need the highline. Just manually call up the service reminder, make a note of the miles due and the days due. Then look in the service book, and see when it was last serviced. Then work out the total days from the last service up-to today, and then add that to the days due. Do the same for the mileages. Then if the total days, including those days anticipated by the SID exceed 365, or if the miles exceed 10k miles, then it is on LongLife.
Just making sure a car advertised as being on longlife hasn't been manually reset to t&d by a dodgy owner or the like to stop the light from coming on
Huh - oh, I see what you mean.
But you really need to get the service book out, and do the above calculations. But by going from what you said in the first post, then they would have needed to manually reset it about 8,000 miles ago - because the T&D is NOT a flexible service system. The T&D simply counts down the days from 365, and the miles from 9,600 - and whichever reaches zero first is when the next service is due. It is only the LongLife service which is truely variable.