There's no chance this would reach court. They'll just give you £2.85, at best. If it did reach court it may well be deemed vexatious. Its a complete waste of the court's time and that of the taxpayer funded GTR. You are doing it to harass GTR rather than recover your loss, by your own admission, and you perfectly meet the definition of a vexatious litigant. It's an "unmeritorous lawsuit intended primarily to harass" and you'd probably be ordered to pay their costs.
https://www.collinsdictionary.com/dictionary/english/vexatious
I think when you said you're unemployed, I think you could just as well have said underemployed. There's no incompetence, merely a poorly defined sequence of events that isn't adequately covered by a payment mechanism, because they are not reasonable and genuine actions, your movements were specifically designed to confuse and create administration.
There's no gotcha! moment here and I suggest you find something better to do with your time.