Your spark plug replacements are linked to every third oil service, along with your differential and transmission fluid changes provided you do not have DCT. DCT fluid is lifetime/100k.
You can ask them what the integration level (i-level) your car is and that can be cross-referenced as to which programming version your car has. It can be read out of your key and should be attached to your work order as well. Take checkmate's i-level above and the corresponding version I posted for it as an example.