Home contents insurance may cover theft or accidental damage, but usually not component failure.
TVs are usually supplied with a 12 month manufacturer's guarantee, but I would be surprised if Currys didn't try selling you a extended warranty/repair support plan ([Link: currys.co.uk]
). It could have been the underwriters of such a plan trying to contact you, or a third party fly-by-night outfit trying to scam you. Whatever the case, you're under no obligation to sign up if you don't want to.