That is a huge #fail - I'm so sorry for you.
We fly BA because it's a big airline with backup procedures, not a skimpy fly-by-the-seat-of-our-pants low cost operator.
I'm especially disappointed at LCY ground handling. If you complain make sure you CC LCY - IME they are quite proactive with customer feedback.
Shame all round. Good to be reminded of the importance of thorough travel insurance.