Part of the 15k mile service is a new cabin air filter. It is very easy to do yourself.
Up in the passenger front footwell in front of the lower glovebox plastic there is a foam cover that is held on by 3 thumbscrews.
Remove the thumb screws and remove the foam panel, you will then see this.
You need to slide the white plastic cover to the right (passenger side of the car. If you can't get it to budge you can pinch the section in the middle with the two ridges that keep the cover locked in place.
To remove the cover fully you may need to pull out this foam piece behind the fan motor.
The filter just pulls out and a new one goes in the same way. You may have to contort it a bit to get it to bend, if you have floor mats it is easier to get it in with them removed.
When sliding the white cover back on make sure the filter is pushed all the way up into the housing or you may not be able to slide the cover fully closed (ie the ridges on the white cover need to be on the left side of the black housing).