A colleague at work had similar issues. She would often mix work and personal journeys, so consequently had a mixture of starts and destinations, railcard use and the like, which came to the attention of an "investigator", and she received a series of letters asking her to account for herself. She responded to these, which made matters worse, and the letters got increasing threatening. The stress got to her, and she ended up needing time off work. It ended up with the company secretary drafting an email for her to send telling the train company that unless they were able to present any specific evidence of fare evasion, no more letters/emails were to be sent, any further correspondence would constitute harassment. Apart from an acknowledgment, no further emails or letters were received.