Helen Morgan, Liberal Democrat MP for North Shropshire, has urged any families planning on travelling abroad to get their passport applications in early.
The passport office is currently trying to work through a huge backlog in the number of passports after applications following the pandemic and Brexit.
Mrs Morgan is warning constituents to apply for passport renewals three months before their intended travel date to ensure they are not disappointed.
The Home Office is still advising people to allow 10 weeks and, while some applications are processed within the period, there have been an increasing number of instances where applications take 12 weeks or longer.
Mrs Morgan said: “Passport delays have been a growing issue but now the situation has reached a genuine crisis point.
“Around one in five of the hundreds of emails I’ve received in the last week have been from people desperate to find out why their application has not been dealt with.
“My team have been doing their best to help – but the Home Office does not answer the phone and takes weeks to reply to emails, whether they come from customers or MPs.
“Therefore it’s really important that anyone who has a trip booked gets their applications in early and makes sure their application is filled out correctly.
“I have written to the Home Secretary to call for action to be taken to improve the situation as soon as possible but, as it stands, the Home Office is clearly not fit for purpose.
“Therefore it was concerning to see reports this morning that the Government is now planning cuts to the number of civil servants working on issues like this.
“However MPs from all political parties are frustrated at the situation with the Passport Office, so hopefully the Government will realise the severity of the situation and act accordingly.”
Many countries now only let people enter with passports with three or six months left before they expire – another reason for people to check the status of their passport.
Mrs Morgan said she had been inundated with requests for help from constituents over the issue – leading to a 25 per cent increase in her office's casework.
She said one man had only received his passport three days before he was due to celebrate his wife’s 50th birthday this month, despite lodging the application back in February.
She added that another family are still waiting to get a young girl’s passport through 13 weeks after applying.
It means the family is fearful of having to cancel the holiday for a second time, after being forced to call it off the first time due to coronavirus.
A HM Passport Office spokesman said: “Since April 2021, we have been advising people to allow up to ten weeks when applying for their British passport as more than five million people delayed applying due to the pandemic. We urge people who need a new passport to apply for one as soon as possible, with the vast majority of all passports applications are being dealt with well within 10 weeks.
“To deal with this demand, we have increased staff numbers by 500 since April 2021. This has helped us to handle more applications than ever before, with more than one million passport applications processed in March 2022.”
"The passport advice line is being delivered by Teleperformance which is in the process of recruiting additional staff to better service customer queries.”