IMO you're wrong.
Every delivery I've had from DPD has been problem free and they've always delivered within the 1 hour time slot.
My experience has been the same. DPD are the only courier I trust without having a corporate contract.
Yodel, on the other hand....

At least I've used my work's address, so should be ok. Psychiatric hospital, admin building there with a big sign that says "deliveries", can't miss it.