A friend was booked on a BA itinerary for CPH-LHR-SFO in Premium Economy.

The weather in London and Copenhagen was fine but apparently the CPH-LHR leg of the flight was delayed because the incoming plane for CPH was from Zurich which was delayed due to snow. This caused her to misconnect in Heathrow.

An incredibly unhelpful BA Agent finally managed to rebook her on a United flight that connected through Washington DC but the ticket was in economy and not premium economy, and she arrived in SFO at 1:30 AM which was more than six hours after she was originally scheduled to arrive.

What is the best way for her to seek compensation/reimbursement? Does anyone know if she should be entitled to a 75% refund on the full ticket price because of the downgrade plus the €600 in reimbursement for the delay? She also has Emerald oneworld status through AA. Will she also have to apply for original routing credit for the correct number of miles be credited to AA?

Thanks!