Nearly seven in 10 shoppers had problems with Christmas deliveries last year, with tens of thousands of items going missing in the most, new figures reveal.
Parcels lobbed over fences and allegations of fake signatures were among the issues highlighted in a report by Which?.
Some 69% of people surveyed said they had at least one problem - while a quarter said their deliveries failed to arrive.
Almost a fifth told the consumer group their delivery arrived late last year, while more than one in 10 did not receive their delivery in time for Christmas.
Other problems experienced included parcels being damaged after being thrown over fences, a clothes delivery ending up in a food waste bin and a parcel left out in rain, where it was chewed by foxes.
One shopper claimed that their signature had been forged to suggest that they had personally accepted a delivery, when in fact it had been left on their doorstep. The customer had been inside waiting for it to arrive.
And someone said a laptop they had ordered never arrived but had apparently been signed for the month before.
Adam French, Which? consumer rights expert, said: "Christmas is when we really want parcels to arrive on time - but unfortunately it's also peak time for late, damaged or missing deliveries and we have heard stories of shockingly bad service from the big courier firms."
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Many shoppers have relied on online deliveries during the coronavirus pandemic.
In a separate survey, Which? asked more than 13,000 members about their experience with major couriers between March and August.
UPS was rated the worst courier for keeping customers satisfied. Around one in four UPS customers said they were unhappy with the delivery slots offered and how the company communicated with customers, and one in 10 said they were not pleased with where the delivery driver left their order.
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UPS said that the safe handling and delivery of all parcels in its care is its absolute priority.
A UPS statement, said: "At UPS, we deliver an average of 20million parcels per day around the world and pride ourselves on our service quality and reliability. As a matter of company policy, we do not comment on third party research."
In terms of how quickly couriers delivered orders, Amazon was rated top, with nine in 10 people satisfied with the length of time between ordering and delivery.
For communication with customers, Amazon also finished joint top with DPD, with the highest proportion of satisfied customers in this category.
DPD was also rated top for delivery slots, with more than eight in 10 happy with the slots offered for their most recent delivery.
Royal Mail had the most satisfied customers in the category for where deliveries were left, with more than nine in 10 happy with where the driver left their most recent parcel.
The report found all delivery firms in the survey performed well on maintaining social distancing guidelines.
The consumer group said that if a delivery fails to arrive, customers should immediately contact the retailer, which should either help track down their order or send a replacement.
Dodgy deliveries - your rights
Here are six consumer rights tips from Which? if your delivery has not gone to plan:
If your order is late, missing or has turned up damaged, Which? recommends that you complain to the retailer even if you think it is down to poor service from the courier - because your contract is with the retailer.
If you paid extra for special delivery and your order arrived later than agreed then claim back the extra delivery cost as the service was not delivered.
Be aware if you give permission for your delivery to be left in a specified safe place or received by a nominated neighbour and something goes wrong, you will still be considered to have received the delivery.
If your order arrives damaged or faulty, you have a right to refuse it and get a refund, repair or replacement. Understand your next steps if your goods arrive damaged in the post.
Your delivery should be made without undue delay and within 30 days from the point of purchase unless you and the retailer agree otherwise. This is stipulated by the Consumer Rights Act 2015.
You can also cancel, within 14 days of receipt of goods, an order for most items bought at a distance - for example, online, over the phone or a mail order catalogue.