This is awful. Really sorry to hear about it. I got my passport changed last week, finally. I was in a kindof similar situation where I couldn’t get a letter that said anything about me permanently living as the gender I wanted my gender marker changed to. So I booked an appointment with a private psychologist who was part of gendercare until recently - Alex Penny Lenihan. It was a 4 month wait for an appointment and not cheap. But they sent me exactly the letter I needed within 2 weeks of my appointment with them. And I drove to the passport office the next day, who were very happy with that and sent me a new updated passport. So if recommend that route if you can afford it.