I just had exactly the same experience as James, except with Tournament Parking in Wellington.
I don't think it's the fault of the parking people at all, although I'm not saying that Wilsons Parking don't feed on the blood of the innocent (I'm sure they do... they are the worst of the worst when it comes to parking people, but that's a whole other gripe).
I paid my ticket, put it on the dash and carefully closed the door as I alsways do. When I got back sure enough it had been towed for failing to clearly display a ticket. When I finally managed to get to the tow yard, I opened the car and clearly pointed out the ticket which had fallen down into the footwell, but still clearly visible to anyone breaking into my car to let off the hand-brake.
The end result was that they just didn't want to know, didn't care, didn't need to. They just hide inside their bullet-proof room and wait for you to pay them... if you ever want to see your car again you really have no choice. So eventually after trying to carefully explain my rights in this matter and having them explain that they don't know anything about that they 'just truck drivers'. I caved and payed them.
From what I can find on the web it looks like other countries have introduced legislation to control these guys, but NZ has not. The information I've seen suggests that there is no limit on what they can charge you and they can pretty much tow you anytime they feel like it as long as they have a piece of paper stating they can do it... but even then I'm quite sure they tow without it.
Here is a perfectly plausible scenario - an underpaid ticket officer strikes a deal with a tow company and agrees to split the profit of a tow. He writes out a ticket for failing to display a ticket and picks a car at random. The tow company, comes along, breaks into the vehicle, moves or just removes the ticket from the dash, photographs the dash to prove it wasn't there and then tows the car. Under New Zealand law, there's no checks or balances against this happened and there's absolutely nothing you can do to prove it happened and that you're not at fault.
What we have is a legal loophole you could drive a Boeing 747 through. If you could get away with this as a towie wouldn't you? There's virtually zero risk of getting caught and it's a license to print money.
I had another issue with Harbour City a year ago where they towed me from a WCC carpark they didn't have tow rights to. They claimed it was parked in a nearby park they did have rights to. We spent an hour on the phone with them trying to talk to a manager or someone in authority and they resused to pass the call along to their manager also. By complete coincidence we happened to have the Wellington City Council Parking Coordinator with us who also tried talking to them, explaining who he was and asking to talk to the manager, still to no avail. Needless to say he ended up yelling at them over the phone and threatening their entire WCC contract but got nothing from them. I think this clearly illustrates the kind of people we're dealing with here... although I'd prefer not to use the word 'people' because that implies I share the same genetics, which is an insult to the species as a whole.
Is there anything that can be done to stop this legalised thugery?