ESA to UC, permitted work

Hi I don't know if anyone might know about this please. I was on contribution ESA till July and did permitted work, was sent assessment form in June and sent back but not been put in a group still, so my ESA payments stopped in July and I was told to apply for UC, which I did, but since I only have a doctor's note and not been assessed yet they said I am not eligible to get "work allowance" which means they deduct 60% of my wages.
To make it worse this month the money I earned was from work done earlier in the year before I applied for UC, the reason I was paid late was cos my illness meant I struggle to complete paperwork so I submitted all my hours forms several months late, during my UC assessment period, and they are saying cos I was paid in that time then regardless of when the work was actually done they will take it into account when calculating my UC this month, since that was four months work all at once that will mean I get zero UC. Anyone know if I can challenge this or just accept it? Thanks so much