Using compensation voucher
I have a €300 voucher from Airberlin to use on future flights as compensation for a cancelled flight a year or two ago.
Does anyone know if this can be used on flights that are on an AB codeshare but operated by someone else? I need to go from London to Cologne so I can book LHR-TXL-CGN with airberlin but the first leg will be operated by BA. Does anyone have experience with this?
Thanks in advance