So, an update on this -

It is now been 16 days and no refund has come through, despite me being told that it will be back onto my card by the 30th November. It is just unbelievable... I was planning to dispute the charge but was told by Amex that BA will then likely cancel my booking. In summary - refund requested on the 19th Nov for a £100 which they have admitted that they have charged in error. It is now the 5th Dec. I have been chasing constantly holding 30min to 2 hours on the phone each time. I was always told to wait a “few more days”.

Now recently this happened -
-On the 1st Dec one of the advisers have me his email contact and asked me to chase him on 3rd Dec but has not responded.
-Then, yesterday (4th Dec) I was told to expect a manager’s call.
-Today (5th Dec) another adviser claimed that the manager allegedly tried to call me twice today (they didn’t). She also then claimed I wasn’t actually charged anything for this booking, and it was only a hold on my card (despite it being an actual charge posted 20 days ago and Amex seeing ticket numbers linking it back to this booking). I was finally told to send screenshots of my statement. This was done, she confirmed that she has received them, asked me to stay on hold and the line cut off... about 15mins ago. No one has called me back. (Maybe they can’t? - although they have once before when there was an issue).

Here we are then.