IMO, sometimes things happen, but there is no excuse for a consistent lack of communication and over-promising that clearly violates a customers expectations.
The first week of October was also the "Golden Week" in China. Because of that, a chinese company I ordered from online, notified me in advance that my item wouldn't ship until the week after. I was disappointed, but it was understandable. And they didn't do it multiple times, nor did I have to continuously pester them.
Sometimes significant research and testing can take unbounded amounts of time, but even in that case, (IMO) once the previously communicated deadline approaches, it's incumbent on the seller to notify you.