Original ticket is LHR-ORD-LHR, paid A fare of 1980 GBP of which 682 GBP are fees, surcharges, taxes etc. I've already flown LHR-ORD in F. The aircraft for the return leg in August has changed to Airbus 351 with no F. I intend to take the flight. It appears I am entitled to a 75% refund of the fare, however that is calculated. My question is on how to proceed. Do I wait until after the flight to call BA and request compensation or should I call now? Should I complete a form instead of calling and where is the form? How do I calculate what to ask for? How would you proceed? I've read a few other threads but they mainly deal with refunds due to cancellation or not wanting to fly.