Not many contributors on here are so heroic as Mr Hippocrates, but two others need mentioning that do offer to act as representatives, Mr Mustard, and, of course, our esteemed administrator, CP8759. All of these charge no fees, so act as the lawyers say, pro bono, but may well ask for a charitable contribution after a win, or some travel expenses. However, you'd have to ask them. As most adjudications nowadays are phone or (at the TPT) videos as well, there is no travel.
Basically, like me, they are all completely fed up with the venality and rapacity of councils and Transport for London who are ruthlessly enforcing things that really have no traffic management benefit whatsoever, but they get the money rolling in. No doubt the heads of departments involved get substantial bonuses every year too. It's been like this since 1991, so I doubt it's going to be reformed any time soon.