It very much depends on the area you live in as to what services are available. I have a BPD diagnosis, and there are no specialist services in my county at all, whereas others have full DBT programmes/therapeutic communites etc etc. It is truly a postcode lottery.
I am happy to answer any questions you have if you think that would be helpful. I am 26 and was diagnosed a few years ago. I attend a group that is run by MIND, which is the only PD service in my county. I have actually been on a PD training course today, so have spent most of the day discussing PDs and the issues surrounding it.
I don't think it is necessarily a 'rubbish bin' diagnosis, although I do appreciate where that opinion comes from. I do think it is a fairly broad diagnosis, which can cause confusion, and I think it is inappropriately diagnosed not infrequently, but I also think there are people it fits perfectly, and who on receiving the diagnosis suddenly realise that other people think like them, and that they aren't the only person to feel that way, which can be comforting. I think we have an awful long way to go until appropriate treatment is available in all areas, and the stigma surrounding PDs are lost, but I don't think it is an irrelevant diagnosis.
We had someone new start in our BPD group a few weeks ago, and in that session I was talking about the way I think at times, and the new person (who is newly diagnosed) just kept saying 'Oh my god, I do that. Is that a BPD 'thing' - I'm not just weird??' She has said she has found it really helpful to discover that some of the things she experiences aren't just her - they are related to the illness, and other people understand what she is going through. I think that is immensely powerful, and therefore I'm reluctant to just toss the diagnosis aside as being a rubbish/last resort diagnosis, or not real, as I think people who have been accurately diagnosed with BPD do tend to have quite a lot in common, and be able to understand the way one another think. There is a lot of misdiagnosing, but that's a whole other matter.
I really hope your daughter can get the help she needs. It can feel incredibly isolating at times, particularly if you don't know anyone else with the diagnosis, so I hope she is able to find some support soon. Feel free to send me a private message if you want to ask anything, or if you think she may find it helpful to talk to someone else with the diagnosis etc. Good luck!