OP your daughter is a spoiled brat and you are enabling this behaviour through the fact she has no discipline.
She is 12. She is a child and you are the adult.
If you don’t deal with this now she’ll be out of control by the age of 14 and pregnant and possibly on drugs by the age of 16, and you’ll be powerless to do anything about it because she has absolutely no respect for you.
I think most of us parents of teens have been there at some point. Maybe not to this degree, but giving in to something for a quiet life. Problem is the consequences for us then make us wonder what the hell we were thinking, and you will be there soon if you’re not careful.
You need to come down hard. No social media (she’s twelve, she’s not supposed to be on there anyway), no data on her phone, she can call and text only, and for every day she refuses to do so she loses another week of data.
WIFI for school work only.
Cancel the sleepover, and if not cancelling then you drop off and collect.
No pocket money until it at the very least has repaid the £80 she stole, so e.g. you don’t give her any pocket money to the tune of £80 and after that she can earn it through doing chores.
Every time she doesn’t tell you where she is she is grounded. Phone removed altogether if necessary.
My DS is 18 and he still has to check in. Not that I question so much as where he is but we both live in this house and as such there needs to be consideration for one another. And I do the same so it’s a two way street.
I’d be lying if I said that I’d never made mistakes as a parent. We all have, and there is so much emphasis on parenting toddlers that people seem to lose sight of the fact that parenting teenagers is harder. You still have the tantrums, but now they have the vocabulary to answer back, and the intelligence to think they know it all.
But if you don’t take control now then you are going to be the one paying the price later.