I know about the old 'pollen filter' trick because by Father in Law has a Poxhall Arsetra, of which he is very proud, and likes to tell me how well it runs, how 'powerful' it is (1.6 auto hehe).
Anyway he had a ''Full Service'' at the friendly dealer, nice sit down, free cup of tea, sit in a new car, blah de blah, paid up, and went.
A year later ''we'' decided to do a mini service and guess what?........that's right!....... the pollen filter was still the one that Vauxhall fitted at the factory all those years ago
Dug out the old service invoice and there it was........1 x Pollen filter replacement......££££ + VAT etc.
To be honest I can see why they never bothered because it was a right sh*t to change it, not like the easy 406 ones.