Well we now have the council on the hook for telling you a blatant lie. Providing you put the links I sent you by PM to add into the representation, they've not clicked on them and the below time-stamped screenshot shows that as of right now they've still not looked a them:
(https://i.imgur.com/TDeBxUS.png)
Paragraph 1(7) of Schedule 1 to the 2003 Act says:
(7)It shall be the duty of the enforcing authority to whom representations are duly made under this paragraph—(a) to consider them and any supporting evidence which the person making them provides; and
(b) to serve on that person notice of their decision as to whether they accept that the ground in question has been established.
They've obviously not fulfilled their duty to consider "any supporting evidence which the person making them provides", so I think an appeal on this point should succeed.
It's obviously an untested strategy, but it should work (I don't see how an adjudicator would say it's OK for the council to not only ignore but not even bother looking at your supporting evidence) and as they've not reoffered the discount, it's a no-brainer to carry on.
Would you like me to represent you at the tribunal?