Delay Repay - Paper Tickets


Apologies if this has been asked before. I can see lots of posts about Delay Depay, but can't find one specifically asking this question.
I was travelling back from Norwich to London on Saturday 15 August. My train was cancelled due to signal issues and so I only ended up arriving back in London approximately 50 minutes later than intended. I definitely have a claim therefore.
The issue is I didn't retain the paper tickets. I booked online, so I provided the Greater Anglia booking confirmation email. They can presumably cross check that my tickets were actually collected from the machine at the station and that they were used through the barriers at Norwich. However, they have pushed back stating that I need to provide the paper tickets.
I notice on the MSE page for Delay Repay that there is this section:
If you do lose your ticket, the next best thing is proof of purchase – preferably a receipt for the ticket. Failing that, you could try a booking number if you booked online or a credit card statement if you bought the ticket on plastic. There are no guarantees you'll be successful without the ticket, but according to rail regulator the Office of Rail and Road, virtually all train companies will accept alternative proof.
I haven't yet responded to their request for the tickets as thought it would be best to gather any additional info I might need. Does anyone know where the Office of Rail and Road state that "virtually all train companies will accept alternative proof"? I can't see anything about it on their website when searching for "Delay Repay".
Thanks!
Replies
When we have received this information we will review your claim within 10 working days."
This is the request for the tickets that I mentioned in the final paragraph of my original post.
I'm not really sure how to proceed, as I explained in my original email that I don't have the original tickets any more, but that they should be able to see from their own records that the tickets were collected at Liverpool Street Station earlier that day (I booked two single tickets and collected both legs at the same time). They would also be able to see the tickets were then used at the barriers at Norwich station.
Any advice gladly received! Thanks