After an incredible 13 emails, Vodafone decided that I was who I was claiming to be, and refunded my money.

I’m still not sure where my phone disappeared to, or whether it is coming back. They did not offer any explanation for why I bought a phone in their store in Guildford, got it home, discovered it didn’t charge, and took it back to be told no, I absolutely could not have a refund, or an exchange.