Now I know this is anal, but Im bothered by it 
I went to buy some paint from a large diy chain store. It was in the clearance section, with a sticker on it.
The sticker said was..£22.98
now..£5.00
It was handwritten.
Over the top, someone had put a £10 printed sticker, though you could still clearly read the £5 below sticker. It scanned at £10.
I thought this was illegal, and you actually had to remove the sticker if you are increasing the price?
A fiver means a lot to me right now, and Im in a foul mood so want to send a shitogram 