Wasn‘t it written somewhere in the rail privatisation Act that the network Operator had to give about 14 weeks notice, so that tickets could be sold for at least 12 weeks without changes. If this legislation has been amended then I apologise for getting it wrong.
It seems to me if plan was late, Operator shouldn’t have agreed to it (but I guess it is not easy complaining), and Rail Regulator should be enforcing the rules to avoid the Operator having a conflict of interest about complaining
The Railways Act 1993 effectively says "the Secretary of State can do what he wants, when he wants, how he likes to privatise BR and manage the new privatised railway", and not a massive amount more than that. It certainly doesn't go into the specifics of Informed Traveller bidding timescales.
The ORR is involved in these matters, and they must have regard to the DfT's directions in what they do. But ultimately they can't force Network Rail to do the impossible; there simply isn't a sufficient level of resource in place to allow the industry to return to T-12 at the moment. And there seems to be very little interest in doing so, as having the ability to add possessions and change timetable at short notice rather suits everyone concerned.
The issue here is that
despite marking their services as reservation compulsory in the timetable data - and thus having full control over the sale of tickets on their services - Lumo are selling Advances where they haven't finalised their timetable. They are both failing to warn passengers that this is the case, and failing to inform them when changes do happen. All of which is, frankly, diabolical and inexcusable.