If you are within 24 hours of making the booking you can cancel at no charge, call to do it.

1) no you can't upgrade a HBO to non-HBO like that, HBO to CE would be upgradable for the fare difference + change fee

2) yes POUGs are offered

3) what booking class have you got? the lowest economy booking classes Q, O and G can't be UuA'ed. UuA would be avios and tax (extra APD of £13 going from ET to CE)

4) turn up and ask for an AUP if available

5) seems a refund of the seat fee may be due after a AUP/POUG, not sure on bag fee http://www.britishairways.com/en-gb/...|||||L2|||||||