I ordered an item on a Sunday to be delivered to my home address. The next day I received a text from DPD saying that they would deliver it the following day (Tuesday), but not to my home address, rather to Halfords, "as per my instrucions". More than a year previously I had asked for delivery to my local Halfords store, but not this time. Their automated systems had changed my delivery address without my consent.
Anyway, the parcel didn't arrive on Tuesday. Or Wednesday. Or Thursday. Each day, the tracking system said it had been delayed at the Hinckley depot and would be delivered the following day.
I phoned DPD on Thursday, and after a recorded message from the head of customer services asking me to "be nice" because "there's no excuse for abuse" and a 20 minute wait to be connected to a person, I was told that the parcel was being relabelled (again) and would be delivered on Friday.
To cut a long story short, it was only after several such conversations and complaint escalations that I eventually received the package the following Wednesday, eight days after the due date. In addition, I had asked for it to be delivered to a neighbour, but it had been left behind the bins at the side of the house, very visible to anyone walking past. And what's more, the contents had been smashed at one end, most likely due to mishandling at the DPD depot in the preceding nine days.
It was a stressful, frustrating and very time consuming experience, and judging by other reviewers' comments, this sort of thing happens regularly with DPD. My recommendation would be to use a different courier where possible, and to encourage your retailer to do the same.