Whirlpool S20 RBB20-AG Double door fridge freezer no ice.

Model S20 RBB20-A/G
Service no. 8586 152 15000 11 0241 021187

Went out to one of these today.
Never really done that much with them in the past.
Customer reported that it wont make ice. The water seems to work ok, but she has told me that sometimes there are green bits in it so I assume this if because it needs a new filter considering the filter light is on.
She also told me that the fridge sometimes feels as if its not cold enough.
I removed the lower air vent at the front to find the condenser on the r/h side VERY choked up with dust & fluff. Cleaned it up with vacuum cleaner and bottle brush. The ice maker is switched on and the dispenser works as they currently keep buying bags of ice cubes and pouring them into the ice pocket on the door. If I push the infra red sensor in, there is a red illumination on the R/H side and if I move my hand across it, it breaks the ir contact.
Could use a bit of advice on this one please.
Thanks.
Rob.