Your Dd seem very much like mine a year ago, addicted to her phone and games, not able to regulate herself.
I think the question whether to stand back and watch in slow motion your 'adult' Ddd crashing out of education because she is immature and irresponsible, or to treat yourself as as a parent that is going to do what they can to maximise your child's life chances is basically down to your own values. Are you comfortable watching the car crash? If not, if you feel you need to act like a parent, it probably means you know that your Dd is still a child, no matter what the numbers are.
Some people up the thread mentioning anxiety and denial are spot on.
That what was going on with my Dd - feeling of helplessness, doom and "escapism" in her own words. Your Dd knows that with her AS results, her predicted grades will not get her into uni and the whole year 13 is a slow motion car crash. She is anxious, upset and feels helpless. She probably also has some feelings about dissapointing you. My Dd felt like a 'faillue', so "there was no point to try further".
Talk about her feelings, have a caddle, let her drop her pretences, treat her like a child and talk about a real fresh start and a second chance.
Could you try to take her out of Y13 and find a way to go back to Y12, while you still can. It will be almost impossible to repeat A levels after Y13 and when she turns 19. Call all colleges within 10 miles.
It will provide a real fresh start, a real second chance, and, importantly enable to establish a new good study routine as a preparation to uni: no mobile, no wifi, no games while she is working. When work is done she can play. Estimate how much work exactly shee needs every day in each subject, plan her homework with her. Treat it as coaching, development of good independent learning habits, so when she goes to uni, she will have those good study skills.
That worked very well for my Dd, she is very motivated now, likes to say that she is "a good student", she does loads of homework and , yes, I watch over her shoulder from time to time, I am the judge of when she can have the computer
.
You know yourself and your Dd best, so you might not be as directive, but basically listen to your own intuition, which clearly tells you to do something.