If you want to carry on, there are only two possible strategies at the notice to owner stage:
1) Make a plea for discretion, or
2) Try and trip the council up into failing to consider your representations.
Strategy 1 involves appealing to the authority's discretionary power not to enforce, which is a power only the council has (the tribunal cannot allow an appeal on this basis).
Strategy 2 involves giving the council a link to a video or image you want them to consider, and setting it up view a click / view counter so we can prove whether they're looked at your supporting evidence. If they fail to look at it, you can then win on a failure to consider.
The best approach might be to combine both approaches (provide evidence of mitigation by means of a link), but first we need to know if you have any meaningful mitigation to put forwards.
As long as the notice to owner is challenged within 14 days, Sheffield will usually reoffer the discount, especially if you ask them to.