I feel your pain Adywan.
Seems that no-one can necessarily trust any advertising or salesperson's word here these days. And a lot of them don't seem to know what they're talking about half the time when it comes to the technical stuff, where electronics goods are concerned. And whoever said the receipt was the 'guarantee' was obviously wrong in this case.
Sad that customers seem to need to be having to triple check info. they are given when it comes to 'warranty' matters these days.
It's frustrating for you in the meantime, but I've got a good mate who's a decent salesperson for our local 'Currys', and I'll check out what he reckons about this shop and 'Gateways' claims about all this.