Sounds like a right mess! I don’t think anyone is being honest with their answers over the phone. I spoke to someone as well and he said if it gets to wednesday then my upgrade has more than likely been rejected. I also spoke to TUI and they confirmed I would lose out on the holiday and wouldn’t be able to amend the dates.
I have read some Facebook group posts and people have been turning up at their local passport offices 48 hours before travel. They had all possible supporting documents, travel bookings, ID etc and they got seen that day and went home with their passport. But you have to go 24-48hours before travel. I asked whether you can turn up to any office like Liverpool despite your application being assigned to somewhere else such as Durham. they all said their details were with Durham but they went Liverpool and they called Durham office and got it all sorted on the day.
So my advice would be to go Tuesday to wherever is closes to you with everything and don’t leave until they give your passport lol.