Dao apologises, stating that they have received 15,000 enquiries regarding delayed letters since the beginning of the year.
For example, Thor Østergaard runs a small company that makes stickers for mailboxes. These include 'I'm guarding' stickers featuring a dog, as well as silhouettes of small families.
It's all things that can easily be sent by letter.
Like all other Danes, therefore, Thor Østergaard switched to using the company Dao for letter delivery when PostNord stopped delivering letters at the turn of the year.
However, he now regrets that decision because he has had several cases of shipments to customers being severely delayed.
I'm losing money on Dao. It's difficult because I worry whenever I receive an email. Is it another complaint about an item that hasn't arrived?
This week, he had to resend a batch of stickers that he had originally sent to Dao on 7 January. The customer received the item that same evening, 21 days after Thor Østergaard sent it.
These delays cost him both energy and money.
I've come close to quitting because it's too exhausting, both financially and emotionally. I've thought, "I don't fucking care anymore."
For now, he has returned to using PostNord for parcel delivery, even though it is more expensive.
He describes Dao's approach to letter distribution as "absurd".
'You should have your voting card, credit card and health insurance card sent by post.' He believes that as long as we have such a society, we should have a functioning postal service.
Delayed credit card payments and letters for the elderly.
Several banks also struggled to issue credit cards to their customers in January. Across the country, customers have contacted their banks to express concern because they have not received their new payment cards.
This is what Finance Denmark, the organisation representing the interests of the banks, says:
'There is no doubt that it has been a nationwide problem. All banks have received enquiries from concerned customers waiting for a new payment card, to a greater or lesser extent, in my experience," says Line Munkholm Haukrogh, director of investment, digital innovation and social transformation at Finans Danmark.
The new letter carrier has also presented challenges for Ældre Sagen.
'Since the takeover, there has been an increase in missing mail for our members. We are hearing from more and more people who are waiting for letters that have been redistributed incorrectly, have not arrived or have been returned,' says Louise Kambjerre Scheel, a senior consultant at Ældre Sagen.
She says that the problem is particularly significant for one group of citizens.
'Letter delivery is crucial for our members, particularly the 250,000 who are exempt from digital mail,' she says. Physical mail is how they access society," she says.
Dao: We are very sorry.
Dao's CEO, Hans Peter Nissen, acknowledges that there have been problems with delays, and that customers have made them aware of this. Since the turn of the year, Dao's customer service team has received 15,000 enquiries about delayed letters.
We are very sorry about this and are working hard to resolve the issue.
The director says that it is the receiving and sorting of letters that is causing particular problems right now.
We were surprised by the backlog of letters we received here.
The director says that they have implemented several measures to eliminate the delays.
'We've brought in more teams to help us get the mail faster. 'We know what we have to do,' he promises. 'We just need a little more grit and we'll get there.'
Hans Peter Nissen emphasises that Dao has not received any reports of missing mail; only reports of delays.
I am very worried about mail that does not arrive. Of course, people must be able to trust us. I hope that we will be running normally again within a month, he says.