DPD had two parcels to deliver to me on two separate days. Although we were in the house we didn’t hear anyone knock or ring the bell so the parcels were returned to the depot .
This happened my daughter too with one delivery.
If the drivers had any sense they would see cars in the drive, lights in house etc. To go to the back door would surely be the sensible thing to do which would save DPD money as they wouldn’t have to redeliver.