On February 12 I flew from LHR->JFK->GIG. I only received Avios and tier points for the first flight. For the second flight, the following message was posted in my account under transactions:

Ineligible flight - NEW YORK-JOHN F KENNEDY - GALEAO-A.C JOBIM INTERNATIONAL (Y/O)
AA973(Operated by: American Airlines)(Booking ref: YDNLEZ).

I immediately contacted BA and requested points and Avios. After over a week they replied with the following:

"Thank you for requesting Avios and Tier Points for the following flight:

Flight Number: AA0973
Departure Airport: JFK
Arrival Airport: GIG
Date Travelled: 12/02/2015
Booked Class: O

Our Agreement with American Airlines does not include any flights to or from South America in O class before 13 February 2015. I'm afraid as your flight was taken before this date, I am unable to credit your account."

Is there anything to gain in fighting this or should I just try to claim the miles on AA?