Was charged 40 pounds from the Crown Plaza Heathrow T3 to Departures T3. Paid cash. The driver (who was probably an illegal immigrant as he hardly spoke English) said he couldn't write me a receipt. When I took this up with the company office they said the fare should have been 20 pounds. The driver denies I was charged more than 20 pounds.
I have reported this to trading standards and TFL who are investigating.