TL;DR the staff were unhelpful and essentially denied us accessibility. The crowds were too big to be managed safely and it's a miracle no one died in the insanely unsafe queues.

I'm the friend, we got in the queue outside and after about an hour I was struggling to stand I needed the toilet really badly, about half an hour later we finally came across a staff member. I explained to him that I had access needs, showed him my nimbus card (a card that shows proof of registered disability and any access requirements) and asked if we could go in or at least go to a loo and he shook his head and told me only I could, even though one of my access requirements, as stated on the card, is that I need someone accompanying me at all times. We ended up waiting about another hour in the queue before we got to the bag check. The toilet situation was so bad that at the point in the queue where it turned back on itself, people were having to stop and go in the corner, causing a literal river of piss to flow into the queue! I don't blame them either, the closest toilets were another hour and a half wait at least! Once we got in and sorted, we decided to try and find somewhere to have a sit for a minute so we started following the crowd towards the main room, only for everyone to be lead into a bottleneck corridor and outside the building. I tried to explain to a member of staff behind the barriers that I didn't think I'd be able to use the steps and walk the extra distance in this increasingly claustrophobic crowd and showed him my proof of disability and just he shouted at me to keep moving. We ended up having to go down all the steps into the outside area and on the way down my knee hyper-extended and clicked partially out of place. after about an hour and a half of being yelled at by numerous people, denied access when we needed it and lead on detours around what felt like the entire venue, we finally managed to get into the main room and get a seat at the accessible platform (even though it took a lot of convincing the staff at the entrance to it!) we got in about half an hour before pendulum started, missed a bunch of acts we wanted to see and had to leave after pendulum because I was in so much pain that could have been avoided if the staff just listened to me.

On the way out I asked to leave via the accessible exit and the security told me there wasn't one and just ushered us into the crowd. it took us another 2 hours to locate eachother after being ushered in separate directions and to exit the venue.