The same with me. Last month when I was transiting T5/LHR, I checked in Dixons for the price of the iPhone 6 and they had a small placard stating that they were cheaper than their competitors ie £20. When I asked about the VAT I was told its not Duty/Tax Free and no they didnt have any forms for me to go claim it back afterwards. Courteous? Yes. Friendly and interested to sell me an iPhone? Definitely not!