Isle of Man Transport is trying to reassure people its 'Go Card' system for public transport is safe, despite last month's data breach.
In December, a parent logged on to top up their child's card, but entered their number incorrectly, which brought up someone else's personal details.
The Island's data protection supervisor, Iain McDonald, issued an assessment of the handling of the matter earlier this week.
He concluded IoM Transport had not taken appropriate measures to protect the public's personal data.
Mr McDonald also said its unwillingness to change the timetable for bringing the school bus card system in meant testing of it couldn't be carried out properly
The statement says the breach was the result of a brief lapse in process by a subcontractor, which meant the password protection process 'wasn't as effective as it should have been'.
The password system was actually turned off for 26 hours, according to Iain McDonald, after someone working for the supplier forgot to turn it back on again, having disabled it while carrying out tests.
Isle of Man Transport also claims the only information viewed was the person's name and address.
Mr McDonald has told Manx Radio the person's ex-directory telephone number was also revealed, which is how the parent who'd accidentally accessed the information managed to contact the other person.
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