I've actually complained both to the Royal Mail's own complaints service (as available by calling the number on the back of the “sorry you were out” cards) as well as an indepent complaints service (though still within the Royal Mail somehow) regarding the shockingly poor service over the last few months.
In particular, we seem to be receiving mail for just about anyone (just checked the mailbox and there was another letter to Flat 2, 3 Rainbow Quay – I'll take that to the correct address shortly) as opposed to mail actually addressed to our flat (Flat 3, 2 Rainbow Quay). This happens almost every day, and includes mail for other flats in our block as well as mail for addresses on Rope Street etc.
In addition, they've started not delivering parcels but just leaving the cards instead – When I spoke to the complaints department they refused to take the complaint down because “it has been agreed with the license holder that parcels for the type of flat you live in will have to be collected at the local delivery office”!!
I personally find this outrageous and completely unacceptable as I have paid for an item to be delivered to my door and not to somewhere 2 miles away…
Anyway, I've had a response back on the second complaint and they are investigating – I shall keep you posted!
Sorry for the rant… one of those days…