Have you made a complaint to Asda management yet? Don't start at the bottom. Go as high up the management food chain as possible, preferably the CEO.
When did the terms change at this car park?
Not as yet, i will do that, its worked before in a sainsburys where they had lowered the time allowed for free parking. I am not entirely sure when it changed, i noticed over the last month or two, the top gate which would allow higher vehicles on to the upper ground level of the car park has been constantly locked now, probably so they can catch each vehicle on entry and exit, previously thats where i would drive in and out of the car park, now you have to enter on the lower ground level and up a ramp if you want to park on the upper ground level where the store entrance is, i have looked at the signs now and its clear they have a new operator but then there were signs in the same locations next to the ticket machines, you would stop to look to see if they had been changed, a notice upon entry to the store would of been a good idea so ill add that in my complaint.