No problem

I was on a train when I replied, hence the lack of punctuation.
I am told that Stevenage group has been abolished.
The new routeing guide loaded recently now has Stevenage & Hitchin as 2 separate routeing points.
(e.g. for Letchworth the associated Routeing points are now shown as Cambridge & Hitchin)
However, fortunately there is an easement (number 64) that says the travelling to/from Letchworth/Baldock to/from Peterborough & stations beyond is valid via Stevenage. Just checked & it has been updated in the version dated 9/9/10 that the easement now also mentions allowing Hitchin-PBO to travel via Stevenage (so the HIT-PBO CDR would stand via SVG without needing the Season as well.)
Interesting.
To clarify, a Hitchin-Peterborough (HIT-PBO) Off Peak Day Return (CDR)
plus a SVG-HIT season is valid on a non-stop train.
A HIT-PBO CDR by itself wasn't, strictly speaking, valid via Stevenage on the basis of the group station rule, because that rule only allows double-backing within the group where both the origin and the destination are out of the group. The abolition of the group makes no difference to such a ticket, but would make a difference to applicable tickets (e.g. Letchworth to Arlesey) however the easement reduces some previous validity but appears to add additional validity for tickets to Hitchin.
Last time I bought this ticket (sometime last year) it was definitely marked "FCC only" so they have changed the fares in the last year.
Presumably this means that for Royston/Cambridge you may now have to go via Ely to reach Peterborough rather than via Stevenage (or change at HIT & use FCC) as the easement does not mention these stations & you would now be doubling back through Hitchin (though having said that the east coast website it still allowing you to reserve seats from SVG on this route).
Yes, ATOC have increased validity for journeys to Hitchin but only if you are going to Peterborough or beyond,, and they have reduced it from many other stations e.g. Shepreth, and those that remain don't have that validity to local stations preceding Peterborough. e.g. Letchworth to Huntingdon.
I suggest you write to Passenger Focus and ask if they approved it. If they did approve it, why did they? If they did not approve it, what happened next?
PF have to be consulted by law on RG changes.
If ATOC are not doing this, then it needs reporting to ORR.
I'd contact PF first thing on Monday if you can.