My own view is that as the discount option has gone, you should now submit representations based on your initial narrative, namely that there had been no announcement about the new parking restrictions, and you have been parking all over the borough for many years. I don't think this is worth taking to London Tribunals unless somebody suggests a 'technical' appeal based on WF mismanagement of the enforcement process, but don't miss the NtO deadline (Pay or appeal). It is probable that they will re-offer the discount, so best not to pay-up until you have a reply to your reps.