Hotpoint Mistral Plus replaced thermistors ,fans not working

If anyone has experience of this problem I’d really value your help.
I noticed the fridge wasn’t chilling things and temp was rising to +14.
Took the grille off at the bottom and cleared out all the fluff (was fairly built up)
On examining the contents of the freezer I could see that the food was begining to defrost.
I pressed FF for fast freeze and the freezer has been showing that on the controls ever since.
Took the grille off at the back of the machinre and did the same.
I noted that the black ball thing (compressor?) was hot and making a noise (just the normal running noise) however the fan was not spinning (it isn’t siezed).
I took the panel off inside the freezer and saw that the fan inside the freezer wasn’t working either.
Having read lots of comments on here and other forums I followed what others have done and purchased 2 thermistors. I duly fitted them at around lunchtime, and now, approx 6 hrs later and the fans still do not work!
The compressor is humming away nicely and is hot, the freezer does feel cold now but there seems to be no action from either fan!
The fridge is now room temp and showing +18 on the display

PLEASE HELP!
Lisa.