The simple fact is that all logistics, in and out of the UK, is in a real mess at the moment. I doubt it'll improve quickly because many firms are deliberately hanging back on moving any goods at the moment. In the same way, tracking systems seem to be horribly behind too. My amps arrived from the US before they were actually due to arrive but the UPS tracking was way out of kilter.
Anyone who gets 'good' service at the present time is lucky. There is fault at the root of it all but it is not down to the supplier, carrier or even HMRC, who are overwhelmed and understaffed.