It seems all you can do with JetBlue is talk to them on chat and I've been going round in circles with them having been told I've been sent a travel credit for my delay. Great, but that's not what I want, and $150 isn't even close to the $600 in compensation they should be providing for having me arrive at my destination over 4hrs late.
I have been sent the following link, but I'm not entirely sure it'll go anywhere:
https://www.jetblue.com/contact-us/share-a-concern
For background, the flight was (on one ticket): LGW - BOS - BNA. The BOS - BNA sector was delayed (4hrs51mins late) due to a mechanical issue (something wrong with an emergecy system). As this flight originated in the UK, I am eligible for EU261 compenstation, as I arrived at my final destination over 4hrs late.
Edit:
Actually, I apologise, I found their reply in my spam from the "Share A Concern" page. They have replied (incorrectly) as far as I'm aware with:
Due to the flight not being a direct flight from the UK, it does not fall into the qualification for the compensation you are requesting.
Next best steps?