I had a phone call yesterday, and they said that it seems to be a driver issue at a particular depot. The driver(s) just kept using the same calling/delivery card every time they scanned to say that they weren’t able to make a delivery, instead of using a new/individual one. Which just somehow made them all linked up. Anyhow, they’ve instructed the depot to make sure that it’s done properly now, so hopefully it’s sorted now.
DPD then also sent a cookie with icing on the top with their logo and the words Sorry and my girlfriend’s name on the icing, so that was at least a nice mini bit of PR to apologise for their mess up. Still quite surprised at how easy a thing it is for something like that to go wrong though!