Retailers are being warned to be on their guard against a scam involving ‘cold callers’ who contact people claiming to represent a Government department or other official-sounding organisations and explain that a substantial amount of money is due for a variety of unlikely reasons such as PPI, a lottery win or an unexpected bequest. The caller says the money can only be obtained by going to the nearest convenience store to buy a Ukash voucher with which to pay their organisation, often described as an admin fee.