I'm guessing you will be lucky to get the rest back, amazed he even sent you as much as £140 to be honest... He hasn't been on here since 26th May either, so has not exactly given you a heads up...
I would do as suggested above and claim through PayPal, when they find in your favour they will claim it back off his balance, if he doesn't have enough in there they will just put him into negative balance and pester the crap out of him...