Aunt won't refund money

Also if your aunt is resident in the UK I’m pretty sure rent has to be declared as income in the UK.

Come off it, virtually uninhabitable and threatening to health is a whole lot worse than "isn't perfect".

Is your aunt resident in the UK? If she is small claims court. I hope you took lots of photos and get everything in writing from the hospital. Photograph her notes if necessary.
No one should rent out a property that’s not fit for habitation. Mould can be so dangerous, children have died from living in mould infested flats and houses. I’m sure your dd will be fine after antibiotics , I’m talking more about long term living conditions. People who make money from renting accommodation I wouldn’t let my dog stay in really anger me. And I was a LL for years.

Do you and your aunt live permanently in England?

If so, you and she are bound by English law and I’d be writing to her asking for a full refund and advise her that if she doesn’t pay you with 7 days, you’ll be lodging a claim in the county court for breach of contract. It’s not expensive to do this and you can do it by yourself without any legal representation.

To clarify: A contract exists between you after she offered the use of her holiday home and you accepted and paid her, regardless of whether you have an actual written agreement in place.

Don’t let her get away with scamming you.

Some people are giving you a really rough time, OP. I can only presume that if they turned up to a holiday villa with stinking black mould, having had no warning, they'd still be happy to have paid for it (regardless of if you get a discount/how much).
I wouldn't be going again. Maybe if all the family the aunt rents to do the same, she'll need to start renting to the public, and then she'll get a lesson in consumer rights.

If she was there two weeks before, was she staying in the house and was it that bad then, did she not notice or has it got much worse since, is it just the master bedroom and how many more bedrooms are there? Are the workmen in the house fixing it or do they think the job is finished. Does your Aunt have an agent or anyone out there who is keeping a check on things. It all seems a bit dodgy and that she is getting ripped off by the builders.

I don't know how much you are paying, but unless you have lost a significant amount I would lay off the court action unless you want a huge family rift. And discuss it calmly when you are back and can talk face to face. How old is your Aunt, is she still fully with it? If she didn't think it was bad enough to comment on when she was there, two weeks prior, she may not fully understand the current situation.

I wouldn't be having anything to do with her again, what a horrible woman.

Aspergillosis?

How vile your aunt is
She knew the mould was there yet she didn't mention it and give you the chance to cancel and is ignoring your calls
It's irrelevant how much you paid.
I'm shocked that she risked your DD's health
I actually would take her to the small claims court and would tell her so, and I'm a very placid person, but I hate injustice.
I'm sorry your DD has been made unwell
That is unforgivable.

This is horrific! I would have walked out the moment we arrived and had to have stayed somewhere else, anywhere. I have seen what mold does. To those saying just sleep in the room, nope. Fungal pneuamonia is nothing to be sniffed at OP.

If you’ve got 100% proof the mould caused the pneumonia

then take your aunt to court

you’ll win the money back

this is fungal pneumonia. Does this really sound plausibly like what your daughter has??!!?!

www.verywellhealth.com/fungal-pneumonia-5179190

A pink solution of potassium permanganate (possible spelling error) might sort this by applying it to the outside bricks

I do think it's a possibility. My dd got bronchiolitis when she was a baby from the black mould growing in the old damp house we were living in at the time.

I mean there’s not a lot legally you can do.

do you have holiday insurance?

otherwise paying a family member really unless you want to pay a lot to take her to court there’s not a lot you can do

Not sure what you can do about it now, but your aunt is a piece of work.

Send a formal letter with the confirmation from the hospital asking her to refund immediately and say you would also like your alternative accommodation, flights and damages paid if she refuses and you will be going the legal route.

You cannot get pneumonia from mould. You can very rarely get Aspergillosis but only if you’re severely immunocompromised.

www.nhs.uk/conditions/aspergillosis/

Of course they can't fly home yet if her daughter has pneumonia. Cabins are not pressurised to sea level. Meaning the risk of hypoxia, even if just coping in air on the ground.

She should be reported as the place is not habitable

Is the property in Turkey OP?

hope your dd is on the mend.

Outrageous behaviour. No one should be staying there. Doesn’t sound like she cares so I doubt she’ll pay. Sad state of affairs.

Oh my goodness that is absolutely horrendous. And your poor daughter!

Why is your DH engaging with her when she is your Aunt? Surely your the person to do it?

I would be so tempted to put those photos on a family whatsapp chat - just to make sure that anyone who has booked her house is fully aware of what they are in for - but then I am petty like that.

Apart from warning relatives of the potential to ruin their holiday you could also mention (in passing) that she charged you the full amount even though your child ended up in hospital etc.