my drivers licence has me mums address on it, so I've been told in the past to take me license and also a bill to verify my address at my house (where my membership is registered)
anyhow, she took ages, came back and said that although I'd provided a letter from Santander which was recent and had my registered address, they need a council tax bill in the future. She said that they'd had people who've given them photocopies of address ID in the past. what I assume is that they thought the letter was fake and that people have doctored addresses or information on their address ID.