I would suggest to calm down, try another card as others have said. BA’s phone circus system is not exactly flawless, and I have been in the same situation as you - actually worse, since my booking was not ticketed in time, so was voided altogether.

I would hope your writing ‘tone’ does not reflect that of when you speak to BA’s reservations agents - if it does you may not get much willingness to investigate beyond ‘computer says ok’.

Be constructive, and I am sure there will be a solution. If I remember correctly, the problem in my case was two factor authentication on a credit card, requiring an OTP. Could it be similar in your case?