I'm sorry, this is a bit long, but I'm pretty wound up about this.

I drive a commercial van for my own business, which is film and video making. 4 days ago on a new project in Bristol I arrived as agreed at the rear of a club at 8:10AM to unload a large amount of camera and other equipment to set up for filming. This was carried into the club through the adjacent doors by many helpers in about 15 minutes. There were no other vehicles and it was not a thoroughfare. I was told I could unload but couldn't park there (the area is privately owned presumably by the building landlords) so moved off at 8:25 to find a parking space, which I did in a nearby APCOA car park.

However, the ticket machine only accepted coins and I did not have enough (£5) for the whole day. I did not wish to leave the van there without a ticket so returned to the loading area near the club to find change. I met the producer but he had none so he offered to go with me to a nearby coffee shop for change and also pay for the parking (the coffee shop was next to the club). This was just before 8:35, and we discussed the days work on the way. As a courtesy to the coffee shop he also bought a drink for me to take back and we returned to the van no more than 3 or 4 minutes later - at 08:38 in fact, since I can prove this.

On our return I found my van blocked in by an apparently unmarked, very dirty white van with the side doors open. Thinking this was someone else from the crew I asked the driver if he could move so I could park in the car park. In reply I was told in a very aggressive manner that I couldn't as he was clamping my van. He then went on to say I would have to pay £185 to release it. At this point there was no indication I could see what his vehicle was or who he was and there was no clamp on my van. Both I and the producer objected, verbally not physically, and he became pretty aggressive, threatening me with removal of my van and a further £250 even though he hadn't yet put the clamp on.

When I told him I had just finished unloading and had gone for change for parking he returned to his van, took the clamp out and started taking photographs of me personally and then my vehicle. I found this very intimidating. He claimed the drink in my hand was evidence that I had parked. He said the sign was clear that parking was not permitted - the sign was in fact on the wall of the building at the 2nd storey level and I admit I hadn't seen it. I kept at least 2-3m away from the guy as I felt physically threatened so I decided to take my own photo's, of him, his van and his activities and the time.

He clamped my vehicle, returned to his van and told me unless I paid within the next couple of minutes he'd call the removal truck and have me towed away. Another van had arrived in the meantime who parked next to me. I asked the clamper if he was going to clamp that guy as well. He said he wasn't because "he was with his vehicle". There were no other vehicles, no obstruction and no-one else was trying to use the area.

Since I couldn't move the van, and I was the cameraman for the project and we had over 20 people waiting to start the shoot upstairs in the club, I had no choice but to pay. I did so under extreme duress, using a debit card. While he was doing that I took more photo's of his van, including the signage which had now appeared on the vehicle. When the producer told him he'd had no signs on his van and this was likely not legal he denied this was the case. However, I have photo's which show the contrary. It is my belief, although I do not have proof, that he was in his van, unmarked, near the club watching and waiting when we arrived and unloaded.

He finally removed the clamp, I moved my van to the APCOA car park, bought a ticket and walked back to the club. The clamper was still there talking to the electrician. It was now about 9:00 and I'd lost over 20 minutes of my set-up time and £185 out of my bank account, for doing my job and trying to follow the parking rules.

In 35 years of driving I have never had a parking ticket to pay (I have been given two, each of which I politely disputed in writing and they were waived) and I have never been subjected to such aggressive behaviour from such an individual. It says on their "ticket" that I have 14 days to "appeal" in writing (to a PO box). However I am so disturbed by the whole incident I am considering what other options I may have especially as I have both witnesses and photographic evidence of events. I was very intimidated and honestly felt I was being robbed.

What do you think - any advice? I have 10 days left to "appeal".