Indeed - check your Co-op receipt! Last week (28/9) I bought a new large tube of pringles for £2.04, but when I got home and checked my receipt the item had scanned through at £2.49.
I went into the shop today (5/10) and these crisps were still being displayed at £2.04 and scanning through at £2.49. Bryce is now aware of the error, but if I'm in the store this Fri/Sat, I'll double check!
I'd only bought a few items and recalled the price of the pringles. I guess it's impossible to check you're not being ripped off on a large shop - it's not possible to remember the isle price of everything you buy.