I've had Amazon Prime for several years and it makes no sense to me that they still use Dynamex as a courier. I have yet to have a package arrive on time, and in many cases, at all.
With 611 bad reviews on Google about this Courier all related to Amazon deliveries, why on earth is Amazon still using them?
1.3 out of 5 stars is the average... complete waste of time.
Amazon... wake up and pay attention to your customers. If you cannot offer same day or next day delivery because this is the only option, then so be it... I would rather wait then to have to deal with this very incompetent courier.