Sorry for the late response and thanks for all of your help.
The penalty fare is attached here but it still doesn't seem to be on their system, so hopefully they made a mistake or forgot to upload it. I doubt they'd prosecute anyone over just £52.50 so hopefully that's not happening.
On Thursday I got charged a penalty fare but when I typed in the reference number today nothing came up and when I called them they said it wasn't on the system. What should I do next? Does this mean I won't have to pay or should I still do something about it?