Just recived this speedy response from the Post Office complaints people:
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This is an automatic acknowledgement from Royal Mail Customer Services
Your reference number is xxx-xxx (my change)
Thank you for your e-mail regarding lost, damaged or delayed mail.
We know how important it is for all mail to be delivered on time and
without incident. We would therefore like to apologise for any upset or
concern we may have caused.
We are unable to process claims for loss, damage or delayed items via
e-mail as we require your signature of declaration on our claim form and we
also need certain original documents such as certificate of posting before
we can consider your claim.
We therefore need you to complete and submit a P58 lost damaged or delayed
mail claim form for each item of mail affected. These forms are available
from all Post Office branches or alternatively you may wish to download and
print a form from our website by clicking on the following links.
For Mail sent within the UK
ftp://ftp.royalmail.com/Downloads/public/ctf/rm/Inland_P58_form_English.pdf
For International Mail
ftp://ftp.royalmail.com/Downloads/public/ctf/rm/International_P58_form_English.pdf
Once completed please post the form along with any other requested
documentation to our freepost address as detailed below:
Royal Mail Customer Service
Freepost
PLYMOUTH
PL9 7YB
What will happen next?
Once we have your completed form back you will receive an acknowledgement
from us providing you with a unique claim reference. We aim to conclude
all inland enquiries within 30 days of receipt and with some are in a
position to do so even sooner. Having said that part of our enquiries may
involve contacting the recipient and them being given time to respond - so
it is appreciated if you allow us the full 30 days after receiving your
acknowledgement before re-contacting us.
This has been allocated to one of our advisors who respond to your specific
enquiry. Our aim is to reply to all customer emails within five working
days.
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Would be quite impressed with the speed of response if I had actually complained about 'lost, damaged or delayed mail'.
However my complaint was actually about the length of time I waited at Oxford Post Office to post an item on Monday afternoon!