OK, so you have some good points to present, but you'd have to present them to an adjudicator, because Havering will not give way, nor re-offer the discount so you have a choice, (1) cough-up the discount without submitting reps, or (2) stand your ground, submit reps, and when they're rejected, register an appeal at London Tribunals.
I think the chance of success is not slam-dunk, but pretty good as the kerb-blips are so worn. These must be there so you know when parking that there is a loading restriction without having to trek all over the place to find a possible sign.