Here is a little DIY on how to change your pollen micro filter...
a new pollen filter from BMW cost me 40 euros. It was a simple ten minute job replacing it.
All you need is an 8mm 1/4" socket to remove the six sheet metal screws. There are two screws on each duct - where it meets the bulkhead and two screws up front by the cowling. Once all six screws are removed the filter housing will be free for removal. The new filter just snaps into place. Easily a ten minute job - max.
Dackel