I'm going to suggest an unconventional approach, though it is ultimately your decision how you wish to proceed.
Essentially we know that Tower Hamlets of all places will never grant a discretionary cancellation based on the grounds you propose to use. However by saying you paid via RingGo, you're admitting that you were aware of the requirement to pay, which in this case is a somewhat unnecessary admission.
In essence we want this to get to the tribunal without the council giving the case any real thought or consideration, so if it were my PCN I would:
1) Ignore the roadside PCN and just wait for the notice to owner
2) Make a one line representation against the notice to owner saying that contravention did not occur
3) Make a one line appeal to the tribunal saying the contravention did not occur
4) Wait till the day of the hearing and then point out to the adjudicator that the photos do not show any contravention (though it would be best to have someone represent you because otherwise the adjudicator can simply ask if you paid / if you knew you had to pay, and you must tell the truth).
This could be seen as a high risk high reward strategy, but I can't see how else you could beat this particular PCN.