If someone wants to start a thread I will share a tip on finding plutonium, its not the best way to get it and there's still quite a bit of luck involved (I'm keeping that under my hat until the challenge is over) but it might help someone that is really stuck.
I have a question too - if you're on vacation on day 4 and you use your phone to 'return home' at 8:01pm but then your sim stands around for 4 hours (00:01am the next day) does that count as 5 days or 4? In my tests I haven't found any common cause of the 'stand around for hours' after calling to return home, it doesn't always do it, some of the time you go home straight away, other times you stand around for something like 1-4 hours.