Well it will take some time to get the details I've requested back from the council, but send this on Monday 10 July (not before) to buy time:
Dear London Borough of Newham,
I contest liability for PCN PN36080473 on the basis that the alleged contravention did not occur. The photos taken by the civil enforcement officer show the car and the sign, but not where the sign is in relation to the car (or vice versa). In the circumstances, it is not apparent that there is any case to answer, as the sign could have been anywhere and there is no evidence that the signage as a whole was adequate.
Yours faithfully,
Of course the council will reject, but they will also re-offer the discount (in the hope that you'll give up and pay). We should have the details of the traffic order come back long before the extended discount expires.