Q: Brakes: vacuum pump relay failire

It sounds like your problems are isolated to the Brake Assist System which is a system designed to sense panic stop conditions and use vacuum to assist the brake pedal and give you the shortest possible stopping distance. Like the ABS system or vehicle stability control, they go into "limp home" mode when there is a problem, leaving the car in driveable condition, but without the assistance of those particular systems. . It’s just sort of like driving a car built in the 1970’s. The failure of the vacuum assist should not affect the engine. I can’t speak for the safety record of your new car, but recalls and software updates have become standard operating procedure for automobile manufacturers and like your home computer, sometimes the updates solve the problem, and sometimes they lead to more problems. I can only recommend that you try to stay informed as to the latest recalls and updates as they come down the line and have them performed as soon as possible. You should be on the dealer’s mailing list for these updates and recalls. If you continue to be completely frustrated with your new car, Years ago some states passed a "lemon law" that said if you had to bring your new car back to the dealer three times for the same problem, you were entitled to a replacement. I don’t know if those laws are still in effect, but it might be worth doing the research.