I really don't get why people bother paying Taxi rip offs?
Pay with the right money if you're in a situation where once might occur (never happens to me, but coming out of a Q.Hotel, I'd defo have a big selection of small notes) and just walk away when the shouting starts (after you've got a photo gof the metre and the drivers ID - if you can even be arsed with that) - Just walking away and telling him to call the police is surely enough.