Apparently...

I’m the only parent who builds and mends our wheelchairs and advises wheelchair services exactly what we need and why ;-). I even had the spanner on me that they needed. Been to wheelchair services for a new seat today. Hopefully it will work as the last new one put him back to screaming and locked spasms in less that 8 hours. This one is exactly the same measurements as the one he’s been managing in just with better pressure cushioning. Fingers crossed.