Hello mate, I used peterboroughupgradeteam@hmpo.gov.uk, but this will change depending on the office that is processing your passport (if its liverpool etc you just change the name of the office). I don’t know if this makes a difference, but this is the way I structured the email:
Subject: Urgent Upgrade PEX (number)
Following a call today with the advice line I was advised to contact you to upgrade the applications for my passport as our date of travel is on (DATE), 2 weeks away (please see evidence attached, flight reference).
Please see details below:
Name of applicant:
Date of Birth:
PEX number
My contact number is:
Make sure you’ve attached evidence of your travel (flight confirmation etc) Hopefully this helps you get sorted, don’t spend hours on hold with the ‘helpline’ as they are about as much use as a chocolate fireguard. The upgrade team do work in datal order allegedly so if you’re travelling on next Friday you should get a call Wednesday/Thursday (huge stress I know)