I doubt the council are forcing them to bump up the price to £6 though. £2 was acceptable, but then it went to £4, £5 and now £6...
The way Thorpe implement it is awful as well - the last thing you want at the end of a day out is to have to queue up in traffic to get to an understaffed barrier. With a price increase I think it is fair to expect a suitable number of staff manning the barriers, as the traffic delays caused by passes/tickets not scanning with only one person to help are unacceptable. The same issue occurs at CWOA on a regular basis with no-one staffing the exit barrier (at the back of the grass car park).
Regarding reinvesting the money, CWOA need to do something about the exit from the grass car park, I hate to think of how many cars have been wrecked on that awful mud road! Also, as has been mentioned, the lighting in Thorpe's car park is a safety risk aside from being a pain to find your car in the dark!