My experience today is bothering me on more than one level. Basically, I bought a cheap stamp from
ebay, and received a card through the door saying insufficient postage had been paid. So off I went to the sorting office to pay £1.50 and find out what the problem was.
Apparently ... nothing. Even the guy in the sorting office was mystified. He slipped the envelope through the measuring slot no problem. It contained nothing of size or weight.
Here it is:

Nothing I could do apart from pay up!
Two more things bug me. First, they haven't even cancelled the stamp! It was apparently underpaid, but then they are giving me 55p worth of stamps which (I know I shouldn't, but...) I can use again. In other words, by not cancelling the stamp they are giving me more than I could possibly owe them in underpayment.
Secondly, look at that bright yellow sticker. Britain's had some attractive postage due stamps in its time - some even issued in presentation packs. And this is what it's come to...

OK, rant done. But I'm still peeved about the whole experience!