I was not aware of this until today so am sharing the knowledge. Apologies if in wrong area and needs moving.
I purchased a freezer from Currys last Thursday, online. I was in the store today and notice the price had dropped by £20. I mentioned it to a salesperson and he said if it was within 7 days and I had the receipt on me, he would refund me the difference. As it was an online order, I had to ring customer service who immediately offered the refund! The cost of a phone call, albeit to an 0844 but was only on there a couple of minutes. Hope it helps someone else out!