Stamps!
I received a card through the post saying there was a 'package' which couldn't be posted waiting for me at the sorting office. I hadn't ordered anything so was intrigued.
Turned out to be a wedding invitation which was 1mm too thick for a first class stamp and they charged me a quid to pick it up. I was on the dole so 'every little 'elps' and so emailed the complaints dept. After a bit of email tennis they sent me a book of stamps - result.
( Geoff the Clownfish You know Myra, some people might think you're cute, Thu 2 Sep 2010, 15:27, 4 replies)

Yeah, I had the same thing
Letter (and magazine) from the Labour party was too big to fit through my postbox, so I had to pay an entire pound of money just to get it redelivered. How unlike Labour to make me, a poor single person, pay for their fuck-ups.

Oh...
( Pretender, Thu 2 Sep 2010, 15:36, closed)

Spooky!
Similar thing just happened to me. 10p short postage, charged £1.10.

I used the "stick stamps to the (delivery failure notification) card, then put card in nearest postbox" option, using up a stack of obsolete stamps accumulated from those £1 books of stamps bought from machines over the years. Anyone else remember when 20p would get it there eventually, and 26p was a First Class stamp? I'm un-necessarily proud of how many otherwise-useless 1p and 2p stamps I used to make up the exact value.
(The Incredible Sulk Finally remembered his password on, Thu 2 Sep 2010, 17:36, closed)

Same here - with a dental appointment postcard with no stamp. Went all the way to sorting office for that, took one look and groaned loudly. Luckily our local sorting office are really good, chap on the desk let me have a good look, then said 'you can refuse to accept it you know.' I gave it back and he chucked it in the bin! Top bloke!
(annierat1 doesn't have anything interesting to add on, Fri 3 Sep 2010, 2:58, closed)

My mates Dad is the manager at our sorting office.
dead handy for *ahem customs items and under stamped ones.
(Kip, Fri 3 Sep 2010, 10:40, closed)