Careful; if they are telling the truth, you may be causing your company to be breaching the law.
And if they are not telling the truth then they may be breaching the law , only in arguably a worse way .
The company may be in breach of contract law , the damages for which would amount to a refund for the incorrectly charged ticket .Unless I am mistaken that is the most damages the person could seek to recover
The customer if travelling on an invalid ticket but dishonestly claiming to have authority to travel could quite easily be seen to be intentionally avoiding payment so could be committing a regulation of railway act offence .
Personally I go with the view that as far as I am aware policy is station staff are to only issue authority to travel in exceptional circumstances by endorsing the ticket or in the case of booking offices providing a stamped slip confirming the authority to travel so it immediately poses questions when they are absent and someone is claiming to have authority to travel . I appreciate by law if the station staff do verbally authorise travel then that becomes binding , but in that circumstances because it is not policy to do so it is then arguably the station staff who are putting the company at risk of breaching the law . Not other staff members relying on company policy .I certainly would argue about the fairness of disciplining a guard or RPI for placing the company in breach of the law in those circumstances and have certainly never heard of any staff being disciplined for such
The times I have charged someone when they claim to have been told they can travel would be because upon questioning they have not offered up an explanation that sounds plausible to me or even been able to describe the person they spoke to .The other alternative I always offer is to take the details and report the circumstances to the prosecutions department for them to investigate and they do prosecute in some cases when they further investigate the circumstances . More often than not the choice made is to buy a new ticket or pay any excess due .
This is all a rare occurrence compared to the more regular event of someone approaching you on the platform saying "are you the guard" and "the barrier staff said to ask you if I can travel on this train even though my ticket is for the xx:xx " In those circumstances unless the train is overcrowded the difference in time is ridiculously massive , ticket is for a different day (believe me some do try) or the ticket is for another operators service I will allow travel . And as well as endorsing tickets I will always tell any future guard if I am relieved on route that I have authorised travel for someone with an advance/otherwise invalid ticket . I think most barrier staff know the problems it causes on board revenue staff authorising travel with no documentary evidence .