Poor quality components

Replaced every, EVERY tap in my 30 year old house with another cobra inner. Geysers were replaced too - copper. Yet, the cobra relief valved died after 3 years and the vacuum breaker after 4 years. Each year it's a bit of a mess in terms of water. Geyser fine.... Cobra no longer the quality part you expect it to be? If my Tecron copper geyser will last 10 years, what valves/breakers should I get that are of a similar quality?