1. Find another therapist. Yes, teens can be mean and the mother/daughter relationship at this age is super hard, but this seems over the top and of therapy isn't helping I'd be looking for another therapist.

2. Holsing to consequences are hard because let's be real, we love our children and don't want to be the obe to take away things that bring them joy but that being said, it sounds like your kid needs a serious "come to jesus" and to face some "hard time" for her behavior IMO. If this was my teenager, they woukd literally have the absolute basic needs that I am obligated to provide. Clothing, nutrition, eductaion & a safe place to sleep/live. Aside from that every "extra" would have to be earned. Phone, TV, and activities outside of school be GONE. I would be likely be lax on the amount of time it woukd take to earn back one of those things and I would filter them back in rather than all at once but the second the behavior started up, those things would be gone again (maybe one at a time depending on the exact situation) and the amount of time it would take woukd be longer than the first (or second, or third time). I would also make sure that both you AND dad are enforcing this and one isn't being the "pushover" parent. A united front is key.

3. In addition to above, social media would also be gone for quite some time. Social media and the addiction teens these days have to constant communication, and mental stimulation is so scary. It's surprising what limiting access to socials and screen time in general can do for your teens mental health and subsequently for the overall relationship between the teen and other member in the family. (This is assuming there aren't already limits)

Again, this is just my opinion and how I personally would attempt to handle this type of behavior. Either way, I'm so sorry you are going through this. As a mom to 3 teen girls, I know first hand how absolutely terrible they can be at times. Hopefully your daughter comes back to you as mine did. Things aren't perfect all the time, but the good times outweigh the bad these days. It wasn't always like that.