From reading the posts about this type of experience, I do think that it is important to work with the company you bought your parts from first before posting these types of complaints. Mistakes are made all the time, but it is the willingness to correct them that shows the dedication a company has to their customers. I am sure a company like Z1 understands what happens when they make a shipping mistake, and leave that person waiting to get the right part to build up their Z.
And then there is always the idea that if you dont like how you were treated, shop elsewhere.