Evri and Yodel are the worst parcel firms at helping their customers, while Amazon and DHL are the best performers, according to an Ofcom report.
Although 78% of parcel recipients are satisfied with delivery firms, two-thirds (67%) have had an issue in the past six months, the annual Post Monitoring Report found.
The most common issues were delivery delays (27%), parcels being left in an inappropriate location (23%), the delivery driver not knocking loudly enough (20%), and not being given enough time to answer the door (19%).
Meanwhile, addressed letter volumes fell by 9% to 6.6 billion items in 2023-24, the regulator said.
Despite this, around two-thirds of people (64%) say post is important to them for staying in touch with friends and family, while 82% say they will always need to send items by post.
Ofcom said Royal Mail won back some of the parcel volumes and revenues it lost the previous year because of industrial action.
However, the company continued to make a loss and, while it had made productivity improvements, these were behind expectations, the report found.
Ofcom said: “We continue to have concerns about the longer-term sustainability of the universal service, and we are progressing work on the future of the service, as well as an investigation into Royal Mail’s delivery performance.”
Measured parcels sent by delivery firms across the UK increased by 8.3% to 3.9 billion items in 2023-24, close to the 4 billion pandemic peak in 2020-21, according to the report.
Amazon and DHL achieved the highest levels of customer satisfaction with handling complaints at 56% and 55% respectively, while FedEx slipped to third place with 52%.
Yodel performed “below average” on some aspects of its customer contact processes, Ofcom found, contributing to a satisfaction score of 38%.
Evri once again achieved the lowest levels of satisfaction, despite improving on its 2023 performance, to 32% during the last year.
Ofcom said it had seen “early signs of improvement” under strengthened regulations to encourage firms to treat customers fairly, with customers having cause to complain about a delayed parcel falling to 19% from 23% last year.
Ofcom said: “We expect further, sustained and continued improvement.
“We remain particularly concerned that disabled consumers and those with limiting conditions are still more likely to encounter difficulties with the delivery process (71%) compared to other people (63%).”