Yes, if the cost of repair isn't massive then I'd consider just getting it fixed.
If it's a major problem then just be prepared for the case to be a tough one, these dealers don't give in easily and they're well versed in the legal system. Even bailiffs/high court enforcers are not guaranteed to get you your £££ back.
Court fees are approx £300 and you'll possibly want legal advice which can be as much as £100 for 30 mins.
He's a one man band. so I'm not sure whether he'd be more likely to refuse than if it was a main dealer.