BG: <name of BG's company>, good morning
BT: Hello, can I speak to the person in charge of your BT account?
BG: (slightly suspiciously) That would be me, yes.
BT: (long and uninteresting spiel about how they are reducing call charges, and is that OK with me?)
BG: Yes, fine.
BT: Can I check your details? Are you still at <old office address>?
BG: No; we never had a BT line there, either. We are now at <new address>.
BT: (takes new address down) Could you just repeat the postcode?
BG: (gives postcode, which ends in an X)
BT: How do you spell X?
BG: (stunned silence for a moment) "How do you spell X?" It's a letter...
BT: (babbles insanely)
BG: thanks, bye