By Neil Macfarlane & Milo Boyd British Airways customers have had their bank accounts drained by the airline which has been quietly charging passengers twice. Abigail Hall is one of an unknown number of customers who claim they have logged onto their online banking to realise that their account is at zero. Rather than it being an unwelcome January consequence of the festive period, they had fallen foul of an issue with BA’s charging system. “We’re aware of an issue which has caused a duplicate charge to appear on some customers’ accounts following transactions made on 1 January, which is being…