I'm not clear why you seem to think a credit card transaction can be cancelled up to 12 months after the transaction occurred. This is nonsense, unless you are saying fraud took place. It seems to me that, mercifully for you, you got him to pay for most of the materials for the job up front (and presumably these materials are still on his site).
As to the £7000 you are owed, you are going to have to contemplate taking some kind of legal action to recover it - if you think he just won't pay and has personal assets that could be drawn on if you won the case in court.