Managing a team at a wholesaler that despatch tens of thousands of parcels by various courier each year, I would suggest 3 to 5 days is a realistic time for dpd to search and resolve to Hattons (their customer). This is frustrating and annoying for you as Hattons customer but does reflect the time it takes for :
1)Hattons to go to dpds central customer service team
2)them to track it and go to both the depot it was last tracked at and the one it was destined for
3)they can both conduct searches both in the building and any parcels left on every van when they return in the evening
4) any other depots can scan any misrouted parcels
5)the results of the searches can be relayed to central customer service
6) customer service can relay to hattons
7) hattons can decide on a course of action, based on good faith in the info from dpd and revert to you.
It could be something as simple as the label wasn’t flat and a conveyor has ripped it off, Leading to it going to a unidentified parcel stack or placed on the wrong overnight trailer and going via another part of the country.
This is all based around couriers that run on minimum financial margins, and staffing that go with it, in line with everyone’s expectations of the cheapest possible delivery charges.
The only courier I have found that truly take 20 days to confirm lost is Royal Mail, which I believe deliver the majority of hattons orders and is therefore likely to guide their “standard” customer service responses.