I have been following this thread with interest as I too received the 'letter' recently. At first I thought it was a mate on a wind up as it was printed on flimsy paper with scanned letterhead and not stamped via franking machine. Upon querying it I was provided with a list of the DR claims made, but not the ones they considered fraudulent.
My claims were made direct via GA, not 'genie' or whatever, and I had season tickets in paper form, not smartcard. I also commute from a rural station with no barriers.
Now, I can't remember what I did yesterday, nevermind a train journey year ago. I do about 500 train journeys a year. Some claims may well have been erroneous, but they were rejected at the time. It's likely there were services I DIDN'T claim for; I'm not the type that rushes on to the DR site the minute I get home after a delay. As a season ticket holder I could if I wanted to travel up and down the line all day. Whilst in reality I don't, it shouldn't be for GA to decide that I MUST get the same train to/from London each day, and every claim due to a diversion from such travel pattern is assumed to be fraudulent.
I sense this is a 'fishing' exercise by GA as let's face it the staff must be sat waiting for the tap on the shoulder atm. But sinse I have no way of proving I was on x train on x date, I will agree a settlement to just close the matter.
As others on this forum will attest, the GA service was an absolute shambles at times last year - cancellations, short-formed trains, speed-restrictions etc - so of course there would be an uptick in claims.
If I intended to defraud GA I wouldn't be doing it via a few snide £3 claims for a 15 min delay. I'd simply get on at my station (no barriers, remember), then when I got to London hop on the DLR and alight barrier-free. £5,000 saved p.a.