I had two of the blades I sent out at Xmas "lost". If you had similar problems with the PO see here for the form
ftp://ftp.royalmail.com/Downloads/public/ctf/rm/Inland_P58_form_English_09.pdf
ftp://ftp.royalmail.com/Downloads/public/ctf/rm/Inland_P58_form_English_09.pdf