Refusals of transit can (and I am beginning to think, should) be reported by pilots here:
https://apply.caa.co.uk/CAAPortal/se...?formCode=qau2
I am not some sort of militant right-to-roam pilot, indeed I have on more than one occasion cancelled a transit request after listening to how hard a controller is working, but I did make my first refusal report recently when a previously helpful controlling airport refused me (and to my mind considerably reduced the safety of my flight) when their frequency was not busy. I have had a lot more transits granted than refused (up the Solent is a favourite when I take friends down that way, thank you the ever helpful Southampton controllers for always saying yes) but it does feel that service levels are deteriorating. In this Glasgow case (where I recently had a very simple overhead transit at 5500 which made my flight quicker and safer) where they say "our airspace" rather than national airspace over which we have been granted the privilege of controlling for the safety of our customers but not their exclusive use.
Anyway, use the link, report your refusals.
It's all a great pity, I know that controllers are good people who will work hard to help us in a crisis but the national disease of trebles all round for the bosses and damn the rest of you makes me ever more reluctant to talk to ATC. On my most recent flight around north and east London, it sounded more like Farnborough Radar were acting as traffic police than as aids to safe and expeditious flight (I think that was the phrase when I did Air Law).