Fame Irene Cara
25 February 2011, 15:12
There are claims that passengers are being overcharged more than £1 million a week using Oyster cards on the tube.
The Liberal Democrats on the London Assembly say it's because of faults with machines.
TfL have told us it's down to passengers not touching in and out properly.
14 million journeys were charged at the maximum fare of £7.40 last year.