Not to make excuses for the companies referred to, but like any other deal, as the # of people that are involved between taking and shipping an order increases, so does the opportunity for things to go wrong. Whether it's some specific communication that's needed (like a converter), or an illness, family emergency, facility problem, adverse weather, problem with another supplier in the pipeline, etc,
the real problem isn't always visible to the Customer. All the Customer knows is that his expectations aren't being met. Sometimes this is aggravated by the Vendor not wanting to (or not having the time to) explain his problem or appear lost/overwhelmed/unprofessional; unfortunately that's exactly what the Customer "sees". I don't think anything in business is as easy, simple, or straightforward as Customers perceive. It appears to me that some companies need better micro-management or a more pro-active Customer Service Dept. But you & I end up paying for that, as there's not always enough profit margin nowadays given the focus on Price.
I'm having the same problem with the guy that's a month late on my T-shirts; anink problem's understandable, but not replying to my email makes me nervous. Which then p*sses me off, which then means doing no more business there.