The first time DPD have messed up but in the end shows they are no better than any other delivery company. In my view if you make a mistake you sort it out yourself. You do not expect the recipient of your error to resolve the issue themselves.
DPD returned my item to the seller by mistake despite sending me a notification of the delivery date. I have had to waste my time contacting the seller to rearrange delivery. Obviously this will be much delayed because of DPD. Everyone makes mistakes but extremely poor customer service.