I worked at Comet for 4 years (not as a salesperson I might add!) and I absolutely advise to cancel it, as long as you keep your receipt you get a 12 month manufacturers warranty on the item. The salespeople lie throught their back teeth because they make £5 commission on a 5 year extra cover sale and £3 for every 1 year extra cover they sell (btw did they try to get you to sign up for the items on credit?? - yes even more commission for the store). Your home contents insurance would probably cover everything the extra cover claims to...ahem....cover!
My advice also is if you do go back to the store to get it cancelled don't get drawn into a conversation with the store managers because they'll go all out to try to persuade you not to cancel, they even try guilt trips on customers.
I may sound like a bitter ex employee but I can assure I'm not I left for a better job with more pay and not on bad terms either.
