Hi there OP, commenting as this really resonated with me - I'm 20 currently and struggled so much with acne in my teen years, I tried EVERYTHING - scrubs, acids, retinoids, etc, all my money went into skincare haha.
Would agree with the previous commenter that going to a doctor/dermatologist is a good next step - they are likely to prescribe a retinoid/retinol (my limited understanding is its like a really strong chemical exfoliant, and increases cell turnover), for example Differin or Epiduo (just a warning they are very strong, and need to be introduced incredibly gradually so as not to damage the skin barrier - I've been there and it was so so painful). I've use these before, and purchased them privately a few years ago through boots online doctor for around £40 (don't know if this has changed!).
I later tried to repurchase through the NHS (which would have been free), and they wouldn't prescribe it unless I was on the pill, due to risks with pregnancies - so if your DD doesn't get on with the pill, just a word of warning you may not be able to get it through the NHS.
All of this to say that for me personally, the retinoid route didn't end up working due to the strength of the product (and a warning, the Benzyl peroxide in Epiduo bleaches your towels). That's not to discount it, that along with other things they might offer such as antibiotics or Accutane (horror stories to be found about that one but it can work wonders), may be the perfect thing for your DD.
(UPDATE - just saw that you said the GP had already prescribed her a cream, sorry if i've just overexplained something you already know!)
What has worked for me (and my sister) over the last few years is a supplement from a brand Pore Favor, called their Clear Skin Supplement - its basically a load of vitamins, and the idea is it solves the problem from the inside out, rather than the outside in, so especially works well for hormonal acne.
I was SO sceptical about it at first, seemed way too good to be true (despite the good reviews), as I'd always thought supplements were gimmicky etc., but thought, what the hell, what have I got to lose? They're £25 for a jar which would last a month (cheaper on subscription), so not cheap, but for me well worth the cost. Anyway my skin has never been clearer (I actually get so many compliments on my skin, something my younger self would've been SHOCKED by haha), obviously not perfect, I'll always have some congested pores (bit gross, sorry), the occasional breakout, but that's just what skin looks like. It took me so long to realise that with all the filters and editing going on on social media etc., so I guess just to say to remind your DD that its totally normal not to have perfect skin, and to be kind to herself. Saying that, I know the emotional and physical distress that acne can cause, so I really hope she finds something that works for her!
I use that along with a very gentle unscented cleanser and moisturiser (and SPF), and it works for me!
Sorry for the long thread, just very passionate about skincare 😂Hope that helps in some way ❤