radeng
you should have been Hotac'd plus fed and watered - keep any meal receipts and send them in along with your request for the fare differences F to J
compo for weather delays is not possible under EU rules but downgrading can be considered for compo but only for EU airlines when flying into the UK (but not applies out of so any airline ) - had you been booked on BA68 you would qualify but being booked on an AA flight number and on AA paper you do not
quoted from CAA UK
Sometimes, airlines may downgrade the class some passengers are flying in due to a lack of available seats. For instance, this might mean you are forced to sit in Business Class, despite paying for a First Class seat.
Under EU law, you have certain rights if you are downgraded. To be covered by these rules, your flight must be either:
departing from an EU airport and operated by any airline
or
arriving at an EU airport and operated by an EU airline