Sorry if this pisses anyone off, but I've never had any real problems.
DPD are great around here, I always get a text with a 2 hour delivery window, and they always keep to that. Small orders from Amazon, I always get delivered to the local Sub-Post Office, in case I am not in & because they get a fee for handling it.
Any big items, I ensure when ordering that I'll be home all day for the delivery day - most recent was a new TV for mother, ordered from Richer Sounds, they were using a courier company that I had never heard of before. It went as planned, text the evening before confirming delivery next day, text in the morning confirming a 2 hour delivery slot, and even better, the promised phone call an hour before delivery confirming the actual delivery time, +/- 10 minutes, fucking spot on service.