People in Cornwall have been left frustrated by delays in the delivery of their post.
A number of customers have contacted BBC Your Voice to complain about late or missing deliveries.
Royal Mail executives are set to face questions when they appear before Parliament's Business and Trade Committee to defend letter delivery performance and improvement plans.
The company said it recognised there was more to do to "deliver a consistently high level of service everywhere."
Brian Lee from Camborne, contacted BBC Your Voice to complain about "patchy deliveries".
"I had a first class letter posted at Redruth and it took five days before I got it delivered.
"You know things aren't operating as they used to, but I didn't quite realise that things were that serious.
"First class stamps should be delivered the next day, they should not be able to call themselves Royal Mail - there's nothing royal about it."
Speaking about the message he would want to send to the company, he said: "Just do what they are paid to do, the same what you and I are."
Annie from Hayle said the service was "not good enough."
"We used to have a delivery every day, it was normal but for months now we only get deliveries twice a week.
"So I tackled my postman one day, who is lovely, and asked whats going on, he said at first because they were short staffed.
"Then he said no it's not really that, we have got to prioritise the parcels."
She added: "I said that it's not right, at least if they cut back the services like they have, they need to tell people.
"When I had my birthday in February, it took my cards 10 days to arrive.
"This is not right, this has been done very sneakily and they are not being open about anything - they are supposed to be providing a service.
"Come on guys, pull you finger out - this is not good enough!"
'Backlog of post'
Camborne and Redruth MP Perran Moon recently raised the issue in Parliament.
He said: "Residents in my Camborne, Redruth and Hayle constituency rely on a postal service to stay connected with loved ones, especially given the paucity of our digital connectivity across Cornwall.
"However, residents have been complaining to me about not receiving post for over a month.
"Only to receive a backlog of post containing mail such as medical appointments and financial information."
'Temporary resourcing pressures'
A Royal Mail spokesperson said: "We know how important it is that customers receive their mail on time, particularly when it includes time-sensitive correspondence.
"Recent UK-wide figures show around 92% of letters are delivered on time and 99.4% within a week, which shows longer delays are rare, but we recognise there is more to do to deliver a consistently high level of service everywhere.
"Where there are local issues, these are typically due to temporary resourcing pressures, which can make deliveries less regular for a short period.
"We work quickly to restore a consistent and reliable service."