So far my experience of DPD:
- If they give you an ETA time slot, they'll turn up reliably within that time slot.
- If they don't give you a time slot, but still say they are coming on a certain day, they probably won't actually bother turning up (my experience with an RMA collection ([had to chase it up a few times to actually get them to come]) and yesterdays delivery, which came today right at the start of the time slot)