I think its time to put this fairly simply.
I topped up with £13 the night before, and used one bus. Making my available balance £11.50.
An each way off peak trip by oyster from St MC to Liverpool St via Faringdon is £5.30.
I completed the outgoing journey, no problem.
On the return journey, I was surprised that the tube just rolls onto the train platform which no tap outs (I had tapped in at Liverpool Street). To make sure I tapped out at a stand alone machine on the platform, which said £2.30 (2.40) and I tapped it again (I believe) to indicate I was getting on a train to St MC. At this point, the remainder of my fare home was £2.90. I had £2.30 left, and an available extra overspill at £1.50, totalling £3.80.
The officer asked me about my journey, where I started from etc. I replied Liverpool Street via Faringdon. He must have not noticed the £2.40 taken off at my tap-in at Faringdon.
He demanded I pay £29.70.. and then £9.70. And wouldn't let me tap out, which would have taken off £2.90, leaving me with 90p available credit. I explained my journey, and my brain injury, and that I really needed to get home to take my seizure preventing medication. And that I only had 60p in cash, no debit card etc. He issued me, it appears now, not with a Penalty Fares Notice, but something else, which I now presume was an intention to prosecute. The notice he issued me with started my alleged illegal journey at Liverpool St and not Faringdon, which is probably where he failed to listen in the first place, or check on his hand held device.
When finally I was allowed to leave, I rushed home, very stressed, to take my tablets. As stated before, I had a seizure just under 48 hours later, my first for 10 months, which involved a night in hospital.
I received a photocopied piece of paper, on the 23rd May, asking me to clarify I was the person involved, with an invitation to comment. I attached the reply which I included in my first post, and heard nothing until a 'Single Justice Procedure Notice' yesterday, i.e. seven weeks later.