I have exactly the same problem as I have rung BT 4 times now to try and get BT Openreach to change the postcode as it was a new build address which has changed. I was told once that BT Openreach was not part of BT! Once I had stopped insisting that it was, I was told by Stuart Brown that it would be resolved...He also informed me the department setup to manage the situation like this has been "closed down" I suspect to save costs!
I check with Sky again as it still has not be corrected on BT Openreach.
To say the customer service is useless is being complimentary!