You know what has helped me: watching Wife Swap. Watching the train wreck that other families seem to have. What works, what doesn't, how other people discipline or don't. How change happens. It's really been educational for me. As a result, I've started my kids (12 yr old boy, 8 yr old girl) doing chores. My son is not anywhere as bad as your friend's daughter, but what motivated me is that I don't want to get there.
Anyway, maybe watching Wife Swap would help them. (I also let my kids watch the show. So they can clearly see right and wrong. We usually end up agreeing.) Some families are lovely and need just a little tweaking. It's really nice to see when families change for the better thanks to someone else stepping in.
Jane Nelson wrote some great POSITIVE DISCIPLINE books.
BOUNDARIES with your TEENS by John Townsend would be good for her too.
Well, for now just listen to her. It's a shame she won't listen to you, but maybe it's the delivery. Make her want to ask you HOW do YOU do it? You are obviously doing something right. Unfortunately it sounds like things have to get worse for her to ask you (or reach out to anyone) for help.
For a long time I wouldn't listen to people around me either. But I realized if everyone close to us (2,3,4 people) were saying the same things to me, something was off and * I * needed to change the way I did things.
We hired a parent coach and it appears the # 1 rule is that both parents have the follow the rules and set the example. Guess who wasn't at first? Me. But I'm coming around.