Company incompetence costs the customer

I am deeply disappointed with McCarthy Inyanga Motors in Empangeni, having searched for a vehicle for a prolonged period i found one at the dealership and completed the necessary documentation and validations. To my dismay they realized that they had made a mistake and that in actual fact the car that I am buying is a 2017 model and not the 2016 as advertised, so to remedy their mistake they are now going to charge me extra, I find the practice to be not only insidious but not in good faith and will not be engaging with the dealership in future