is it to late to complain about my assessor?

I had a medical assessment from an ATOS health professional. I had it at home after my partner sorted it for me.I suffer badly with Anxiety & depression i also have 2 Chronic conditions & a heart condition.( I was in an abusive controlling relationship for 18 years,this was 15 years ago but is still affecting me.) I had an ESA Support assessment a few months before .It was fine. But the ATOS one was not,She phoned an hour before her morning appointment I had to get downstairs to answer,she told me she was doing me first as it was easier for her & she would be there in half hour. I stayed downstairs as i find the stairs hard as knee's painful.She didn't check my disability ignored anything i said & kept telling me she knew what she was doing she was a health professional. She based her whole report on the fact i picked up a cup of tea & i looked her in the eye.She was intimidating rude & made it feel like being there was a waste of her time.I spent the next 3 weeks after seeing her report in a state of depression & had really bad anxiety attack.I could not believe the lies it was all rubbish. but i have no proof,i asked them to look again & got a letter back saying they had & nothing changed due to the state i was in after the look again was turned down i was past my appeal date & being told a paper appeal would probably fail,i couldn't get myself or evidence together in time.My life has changed  i'm on standard Daily & 0 Mobility. My partner has been telling me not to do anything incase i loose the lot.This was end of October last year & the only proof i have now got is the ESA medical report is it to late to complain ? (sorry it's such a novel. )