Along the way we got chatting to a guy who seemed experienced in seeing China sites etc so we didn't bat an eyelid when he refused to pay a fee midway through the treck as he said that it was a con and he'd experienced this kind of trouble in China before. The guy stood his ground and nearly ended up getting thrown off the wall (quite a drop) and had a bit of a scrap with the fee collector guy. Still, we stood by the guy and also didn't pay our fee (the collector was far too busy to bother with us). So the ticket collector followed us all the way back to the bus and refused to let the whole bus leave until this guy paid. As you can imagine, this was a very angry bus of tourists. Once the guy reluctantly paid the fee (which incidentally should have been paid it turns out), further money was demanded of him for hitting the ticket collector, which he didn't do. Eventually they agreed to an apology from the guy and we were all able to leave. As both set of people were correct (and incorrect) in their different ways, Rob and I spent most of this time hiding in the back of the bus hoping not to be spotted by either the wall security or the guy.