I do sympathise, as you will see from my earlier entries: it's quite a frustrating problem over here too, of course worse in some car parks than others. I really feel that disabled people have enough to contend with without having to work out the best time to reach the car park in order to find a space or having to hunt around if you don't readily find one. I think we need new legislation so that this kind of problem is alleviated, this would be particularly relevant to car parks with lots of parking overall i.e.: where the able bodied parts of the car park is never full, even at Christmas!
The problem is if there's not a strong backing and law from the government then these companies have free rein to do what they want. It's only when there's a law or legislation that these companies have to sit up and take notice.