Originally Posted by
KARFA
Any dealings with your avios in your BAEC account have been directly with BA. I am unaware of any TA that can process flight booking/upgrades involving avios from your BAEC account.
Interesting, because unless I misunderstand the API's that BA and Avios have recently exposed to developers, that's the purpose of the API's. Quote:
"Our ‘Pay With Avios’ (PwA) APIs allow partners to offer Avios as a form of payment for products in their channels - either as full payment or part payment in the form of a discount."