Today I have news! We know what the problem was/is and I have posted a subsequent post regarding how to solve a hacked AppleIDs purchased apps not syncing to a new AppleID.
Basically as I thought was the case, but I had to be careful what I said to my cousin because it was a delicate situation, it was his girlfriend that had messed everything up. Obviously he was unaware it was her because she did it all on the sly.
Its all quite a messy situation at the moment but at least we know what it was.
I was confused as everything was secure, firewall, network everything but somehow she was managing to change stuff. She was seen outside the house for quite a while at one point so I'm guessing she was getting onto his wireless modem and accessing stuff from there.
Anyhoo... I now have a new problem regarding all this,
see here.