A3 filters - how often do you need to change them?

[vicp]

got an '09 A3 nearing its 1st birthday. its starting to exhibit symptoms of an old cabin filter (musty smell, windshield fogging up, burning smell). i read a poster in one of the forums that he got charged $120 by the dealer to replace his! i'm bringing my A3 in next month for its 1-year service and i'm wondering if they'll charge me labour if i just ask them to do it. also, the engine air filter is locked tight under screws. is that easy to get to? any recos on brands of air filters? should i just buy them (both cabin and air) at the dealership and install them myself? thanks in advance.

[OH9EH4]

what wondering the same thing for my 09 a4

[Crash]

Try youtube. i found one but it won't be post the link.