Well they should have put an icepack on it at least.
Very hard to tell if something is broken or not especially certain smaller bones in wrist.
I fractured same one I think you mean and I honestly thought it was a sprain until xray. It was swollen etc sore, weak but have had more painful sprains.
Can also take while for swelling and can get worse in few hrs so could be big difference between what pe teacher and matron saw and what it was like when she got home.
What is their policy on accidents, do they normally ring parent or only if really ill or head injury?
I would not be livid at school and no point going in furious, maybe speak to year head or whoever you do in these situations and say it was fracture and you feel you should have been contacted during day when apparent it was still sore etc.
Did your dd mention it to other teachers or anyone after matron visit?
They probably thought was minor thing and (not saying this about your dd) some teenage girls can be dramatic about a minor injury so they may have (incorrectly and unconsciouslly even) dealt with it as such.
Does your dd have mobile, could she not have called you at a break or text or used office phone to tell you herself it was bad. She is 13 so not like in primary where only possible for teachers to call home for sick/injured kids.
I work in a school (primary) and our policy would be to ring for anything like you described.
Hope she gets well soon, fractures are not fun.
Ice it (over bandage if she has one) every hour for 20mins when she is up, give her ibuprofen for the pain and keep it elevated on pillow a bit when sitting down and up in sling to support it when moving about.
Did they not even put half cast on it, they did that for me as really swollen and then got proper cast next day, then new cast week later when swelling down as cast got looser after that.
Also give her chocolate and a girly magazine that helps too.
Be civil and calm and explain rationally why you are not happy with how her accident was handled, you still need to be respectful to staff in the school in the manner in which you speak to them. It is possible to make it clear you are unhappy about it and dissatisfied with their actions without going in all guns blazing.