Tabs:
In theory you could claim it wasn't delivered but the fact you've stated it's been received on a public forum won't probably help your case.
I'd contact the RM and complain, your postie obviously isn't playing by the rules.
Don't complain, as the postie probably signed it himslef as he deemed it to be a low value item, mine does that on occasions, the alternative if he played by the rules would have ment you going to the post office to collect them. i would congratulate the postie for using his initiative.