Sounds like the classic overpayment scam - you get paid too much and asked to refund the difference. The cheque goes into your account, and appears to have cleared, so you pay out the extra and release the goods. The cheque then bounces (international cheques can take upto 30 days to clear!) or was stolen, and so not only have you paid out some money but you lose the goods as well.
This is just common bank fraud wrapped up in a nice letter.
Pass the details onto the police - hopefully they will be able to trace this guy through the mobile number provided.
http://www.nhtcu.org/nqcontent.cfm?a...nhtcu&#Q_12402