Agree with the comments already made. A bad dealer can significantly influence your overall opinion of a brand. I know, I worked in the motor industry for many years.
My advice would be to let the dealer know how you feel in no uncertain terms and to attempt to get the required work done before you make any hasty decisions. The Zed is generally a good car and if you can find a dealer that actually cares about it's customers, I think you will be happy to stick with it.