The figures, released under the Freedom of Information Act, prompted watchdogs to call for technology to prevent overcharging innocent commuters. More than 8.3million journeys between November 2005 and December 2007 triggered maximum penalties worth £33million. TfL says it knows of just £803,000 paid in refunds and estimates another £200,000 was returned. It means passengers are failing to check fare details and are oblivious to when the £4 over-charge occurs if they fail to tap out.