Every so often we see a post from someone saying they can't login to BA.com and typically, deleting the cookies will resolve the issue.
I have eventually become fed up of said issue, and in the absence of BA coming up with a fix themselves, I have come up with a solution of sorts.
I have found a Chrome extension called "Remove cookies from site" which adds a button to the Chrome toolbar. Clicking said button, closing the tab and then going to
www.ba.com in a new tab will let you login again with no issues.
For those interested, the extension is available
https://chrome.google.com/webstore/detail/remove-cookies-for-site/lmfdblomdpkcniknaenceeogpgepocmm.
Hopefully some will find this useful, annoying as it may be to have to resolve this issue ourselves.