Good luck with yours, hope it works out better for you now.
I don’t think which carers trust would work, the 3-4 I’ve been told to go to (from various people, not because specifically due to PIP) all just point me at Citizens Advise.
I’ve now applied again for PIP, so should come through in next couple of weeks, then will make an appointment immediatedly with Citizens Advice and hop-skip down there (always fun walking 45mins into an area you don’t know, but at least it’s a straight line!). Then we’ll see how it goes.
I’m going to guess “badly” 
But I’m not really very positive about any of this crap anymore. Too many years of getting nowhere.
Really hope your assessment goes well, so masses of good luck with that. Wondering if I’ll get one this time, when I previously applied, as it was during covid they only gave me phonecalls, which didn’t go well. I dunno if face-to-face would be better for me, but I get nowhere with calls. What legal route could be taken? Is it just as an empty threat to try and push them, or would I have to actually try to do that? Wouldn’t have a clue on any of that, if it’s something that can be done free, or if I’d need to fund a lawyer, in which case, I’m back to my cave on some mysery island somewhere 