£20 for Charge Spoon Titanium?

I went to my local Action Bike shop in Wimbledon, as I ordered a white charge spoon saddle, as it's comfortable as fuck for a cheap saddle.

only to my surprise that the white charge saddle I got wasn't the normal one, it's in fact the titanium one (I notice the logos is baby blue instead of red), they made a mistake in their whole Charge Spoon saddle line-up, they're selling titanium one for £20 instead of £50.

thought I rather like them, so I remind them that they mispriced the charge saddle, but they let me have the white titanium for £20 anyway, result!

If it is advertised at this price then they must sell (if asked) at least one saddle at this price on the day of publication or distrubution of that price (be it in a catalogue, newspaper, website, window dispaly, radio ad etc etc).