Homes in several postcodes have been receiving letters delivered a month late due to Royal Mail delays.
This has led to people not getting vital bills, Christmas cards, birthday presents and sporting tickets in time.
Earlier this week Royal Mail warned of disruption at ten of its delivery offices in the UK as it continues to be hit by staff absences.
As a result, some places may not receive post six days a week as normal, the Royal Mail said on its website.
But several homeowners got in contact with The Mirror afterwards, saying their postcodes were not on the Royal Mail list - despite them having serious issues getting their post.
Andy Potter, 46, who lives in Wimbledon, has been having problems with his post since June 2021.
He has complained to the Royal Mail three times about the issue.
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"Other people in SW19 are getting their post fine," he said. "Whereas some of us definitely are not."
On January 25, Mr Potter got four Christmas cards delivered, as well as football tickets for a match that took place on January 1.
"I now get my tickets sent to my friend's address to make sure I get them," he added.
"I spoke to my postman and he said staff have left and not been replaced - they are short-staffed."
Another Londoner, 58 who wants to stay anonymous, lives in Kidbrooke, south London, and has also been struggling to get post from the Royal Mail.
Speaking on January 25, he said: "We’ve had almost no mail since early December. Since then I have had two or three days where I have received letters. Today, I received two Christmas cards.
"It is not just me, it has happened to several people I've spoken to, and I can see my block of flats is getting less post than it was."
"With Covid and Christmas I understand there will be a degree of chaos around that.
"But from December 10 I have had no letters from any of my energy companies, or council tax bills. It is complete dysfunction.
"I had to ring my energy company to find out what I owed them as I was worried I could be penalised for not paying bills.
"It's my birthday this week and I know four people have sent me birthday packages and none of them have arrived.
"I want to get the paper version of my Covid passport but I am putting that off as I just can't guarantee when it will arrive."
Another homeowner, from Islington, said: "I was expecting last Saturday a delivery from John Lewis as promised but on Monday afternoon it had not arrived.
"The postman said he left a lot of post behind as he had too much to deliver."
If you're expecting mail and it doesn't arrive, the Royal Mail website has a page on its website where it explains its complaints procedure.
There is a webform you can fill out or you can call the Royal Mail on 03457 740 740.
A Royal Mail spokesperson said: “The vast majority of mail is delivered safely and on time. We aim to deliver to all addresses we have mail for, six days a week.
"We are experiencing some delays to service due to high levels of sickness absence, Covid related self-isolation and resourcing issues. We apologise to any customers who may have experienced delays to their mail.
"We have been working hard to get our levels of service back to normal as soon as possible. Anyone who has concerns over the delivery of their mail should contact the Royal Mail customer service team on 03457 740 740 or via the Royal Mail website www.royalmail.com.”
