Airberlin/NIKI's websites are very unhelpful when it comes to finding out exactly what fare class the trip will be booked into.

The only way to find out is to cross check on an online travel agent's website. Look for the same flights/prices/itinerary there and with many sites you should see the fare class displayed. Not ideal, but it's the only way to find out for sure.

I don't understand why airberlin/NIKI don't show this information on their website, especially as it's quite important for those of us who collect airmiles.