If you had a fully refundable airline ticket, then Air France should have credited to your card within a week of your request.
This business among you, Delta, Air France and the Nigeria office – from where I sit, it just looks like a delay tactic, although I’m sure there’s a perfectly good bureaucratic reason for it. The refund should have come quickly from the place you bought it. End of story.
If you ever run into a refund problem again, I wouldn’t waste my time on the phone. You can escalate your case to a manager at Air France by email. The email format is the first two letters of the first name and last name, all as one word, @airfrance.fr (so if I worked at Air France, my address would be firstname.lastname@example.org).
I list Air France’s managers at http://elliott.org/contacts/air-france/.
I contacted Air France on your behalf and it promptly processed your refund.