Good to see all is good!
For the record, and to provide a solution to anyone searching this thread in the future:
AB has an "Amadeus" desk staffed by agents who deal with this on a daily basis. Call them at +49 30-3409 9800 during European business hours. Yes, this is a German number, and not toll-free but the way to go for any seat assignments on AB.
BTW, you list "AA Gold " in your profile - and should not have paid for your seats because AB waives the advance seat selection fees (standard seats only, 'XL' exit row seats are only complimentary for Sapphires and Emeralds) for OW Ruby customers.

edit: This is no longer called "Amadeus Hotline" but simply 'Airberlin Service Center' and is intended for travel agents. Service remains the same. Opening hours supposedly are Monday to Sunday 7am to 11pm CET.