Left on 11 September. Paid in advance by accident. Got new bill!
I was due to switch to Talk Talk on 11 September. I paid the Bill dated 12th September by accident thinking that I was paying in arrears when actually it turns out that the bill date was for the month from 12th September to 11 October when I was no longer with BT, so BT owe me money.
So, BT owe me money, but have just sent me ANOTHER BILL for October to November. What is going on? Also, why does it appear to be impossible to send an email to the BT billing department about this?