Moderator, Iberia Airlines, Airport Lounges, and Ambassador, British Airways Executive Club
Join Date: Feb 2010
Programs: BA Lifetime Gold; Flying Blue Life Platinum; LH Sen.; Hilton Diamond; Kemal Kebabs Prized Customer
Posts: 63,803
I don't know if you tried this, but how about setting up the card first on BA.com / My Executive Club / Manage My Account / Saved Payment Cards. And make it also the default card. In theory you then make the Avios booking, you only need to enter the CVV and it should process fairly swiftly.