Parcels thrown over fences, broken items and packages taken away by bin collectors were among delivery problems experienced by around four in 10 online shoppers last Christmas.
Some 43% of online shoppers experienced at least one problem with their order last Christmas, Which? found.
Of those who had a delivery that went wrong, one in five (19%) was delivered late, one in 10 (11%) was left outside without consent, and 7% went missing.
Among the issues were parcels arriving broken after being thrown over fences – including a crate of wine thrown over a garden gate – packages left in rain and snow and deliveries deposited in bins.
One respondent said they had a courier push their parcel through a gap in the kitchen window, which then landed in a bowl of water.
A separate survey of customer satisfaction with courier companies by the watchdog found all the firms received a score of 80% or higher.
At the other end of the scale, Amazon Logistics and Royal Mail were top of the survey. Amazon was the best courier surveyed for delivering on time, communication about the parcel and the condition of the parcel when it arrived – with at least nine in 10 of those surveyed rating the firm highly in these areas.
A fifth (22%) of those surveyed said they have chosen to avoid a retailer because of the courier it uses.
Customers can be entitled to a replacement, repair or refund if a delivery arrives faulty. Customers may also get a refund from their retailer if they paid extra for a special delivery that then arrived late.
If a delivery fails to arrive, customers should immediately contact the retailer, which should either help track down their order or send a replacement. Ofcom is also currently planning to impose new rules on the delivery sector to improve their services and how they handle complaints.
Which? consumer rights spokesman Adam French said: “Christmas is when we really want parcels to arrive without any hiccups – but unfortunately it’s also peak time for late, damaged or missing parcels and we have heard about scores of delivery disasters.
“It’s important to remember that retailers are responsible for ensuring orders arrive in a reasonable timeframe, so don’t be afraid to make a complaint if you are having problems.
“Ofcom’s proposed new rules for parcel firms are timely, but they must lead to far better levels of service for consumers – who are now more reliant on deliveries than ever before.”
Which? surveyed 2,100 UK adults in February to ask about their issues with deliveries last Christmas and 4,002 UK residents in November to ask about their most recent delivery experience in the last six months.