Eryck,
Depending on how original your car is, you should be very upset regardless of his intentions. I don't know about Hong Kong, but in the USA I would have a reputable and trusted company make the engine bay correct and charge the guy who painted it. If this were done to my car, I would have to be physically restrained from hurting the person. A service provider should only provide the services agreed apon.
Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both tops
1994 E420