I was flying to Houston some months ago and good old G-CIVI had to return to LHR after 2 hours of dumping fuel as the cabin would not pressurize. This resulted in a cancellation and a rebooking via BOS on BA and UA. The total delay at arrival into IAH was more than 15 hours, with the situation handled very poorly at LHR. British Airways initially refused to pay compensation according to EU 261/04 and also stopped communication after the first e-mail response.

I'm based in Germany and therefore was unsure about using MCOL, so I found that one poster here linked to the European Small Claims Procedure, which works up to an amount of 2000 Euros (see the form and process here: https://e-justice.europa.eu/content_...orms-177-en.do). I subsequently filed the claim with the County Court Bury St Edmunds by sending them the form by post. The court contacted me a few days later and asked for my credit card details to process the court fee and to confirm that they had all details in order to start proceedings. Yesterday (9 days later) British Airways contacted me and told me, that they have re-assessed my case and accept my claim for compensation.