just over 2 years ago I had stage 3 advanced/ aggressive prostate cancer, had radiotherapy and now on hormone injection,  just over a year ago, I asked my  company  for flexible hours, from a 5 day week to a 4 day week, it was granted,  with my side effects from the hormone treatment is causing more fatigue, aches and pains, most days the pains are bad due my job having to stand a lot of the time, I have asked to reduce my hours to 3 day week (part time) but they have said due to the operational requirements, they have denied me the request.

can anyone help