Delays to postal deliveries, which some people say have caused them to miss medical appointments, "must be fixed", an MP has said.
Residents in Cumbria have taken to social media to complain about receiving notifications of appointments after they were due to attend, leading the MP for Penrith and Solway Markus Campbell-Savours to set up a meeting with Royal Mail bosses.
The Communication Workers Union (CWU) said the main causes were staff vacancies and postal workers being overloaded with mail which has to be returned to sorting offices.
Royal Mail said: "We are working hard to ensure that all residents in Penrith and Solway receive their mail reliably and on time."
Among the complaints on social media was one from a resident who "missed a medical appointment last week as the letter came this week".
Another said a medical letter relating to their child took 20 days to arrive meaning "they then removed my child from the waiting list because they hadn't heard from me".
Others shared late arriving birthday cards and claimed they were without a mobile phone for more than a week while waiting for a SIM card which had been posted first class.
'Bit of a disaster'
Labour MP Campbell-Savours told BBC Radio Cumbria: "We need this issue fixed. People are very reliant on the mail service.
"If you're missing surgery dates and meetings with consultants and you're elderly and there aren't better ways to communicate, it's a bit of a disaster and I want to see it stopped."
A Royal Mail spokesperson said: "We are meeting with Mr Campbell-Savours to discuss concerns about deliveries in his constituency."
Liberal Democrat MP for Westmorland and Lonsdale Tim Farron said he was also seeing problems in his area.
"This is not the postie's fault," Farron said.
He blamed decisions taken by senior Royal Mail managers leading to an unmanageable workload.
The upcoming closure of the Sedbergh and Appleby sorting offices meant there was more pressure on Kendal and Penrith centres, he said.
The Cumbria and North Lancashire branch of the CWU said there were 10 vacancies at both the Penrith and Kendal sorting offices.
New starters had also left the business due to the "extreme workload" and were on worse terms and conditions than existing staff, according to the union.