I have a mate who got a two turtles a couple of weeks ago. They were both in poor condition, had a white fungus on their bodies that has now cleared up with being kept in clean water, but they both also have white patches on their shell that aren't getting any better. He has been letting them outside to run around in the sun, put a calcium block into the tank (just last night), and is going to replace the light (currently a reptile one but very old).

Is there any think else he should be doing? How long will it take to clear up??

The white fungus is probably bacterial. Keep the lids of the tank to reduce humidity, good nutrition and clean water. It should clear up in time. New reptile tube will help with shell discolouration. You may not notice much improvement until they shed their shells and you see the new shell underneath. You could try some furan tablets. Works wonders on fish with bacterial problems.