Visas – My passport has just been changed to a married woman's name, but the IDL sticker is in my maiden name passport … I will soon be traveling

My passport has just been changed to a married woman's name, but the IDL sticker is in my maiden name passport …
We are booked to travel on December 18th.

I currently live in the United Kingdom with and an indefinite leave visa.
It's in my passport with my maiden name.
I applied for British nationality and the British passport office informed me that I had to change my Aus passport in my married name BEFORE to issue my British citizenship and passport, otherwise I should have them all. two under my maiden name and not being able to change it later (why the hell, I do not know, because I could then send this passport with a marriage certificate and get a new one, but the lady said absolutely not). was traveling and she said to make sure to take my marriage certificate with me and that was fine.
So a long time ago, I booked an appointment in London to get my new passport and the wait lasted 4 weeks.
Whatever it is, while he was cutting my passport with the visa, he told me to check with the Home Office in the UK because I travel at Christmas!
I have been waiting with the Home Office for more than 2 hours without an answer, but I went to Google to see that if my name has changed, I need to replace my visa with a biometric residence permit if my stay is over. 6 months

So it seems that I can not just use my old passport with the border visa to come back and show my marriage certificate, as I was told by the British Passport Service Manager.
It takes 6 MONTHS to get a new visa or £ 839 for a quick visa that I can not afford.
Either way, I will also have my British passport so I will not even need this one!
It seems like I'm completely drunk!
If I take the risk and still try to travel, I do not know what will happen?

I am legally allowed to stay here, I have not done anything wrong, I have followed the advice and I am now in trouble!
On top of that, my dad is old and just passed to the hospital with an 80% occlusion in his arteries, and not well at all, so if I can not leave the country for the next 6 months to Because of this, I have trouble getting away. downhill!

I do not know what I can do?
Does anyone know what it is?
We will lose thousands of pounds on our reserved vacation if I cancel.