You need to have a dialogue with BA about this, and well before thinking about MCOL. My experience is that BA won't hang on to incorrectly inputted charges, so in your earlier call to BA I am assuming to raised a query on this. It's fares related so it has to go to the back office. I don't think your problem is getting the excess carrier fees back as such, your problem may be finding an agent who either knows about Brazil (they may know about the HKG version) and / or is willing to press the case off to the back office team. If the charge is incorrect, then MCOL will be able to look at it, ditto CEDR to a more limited extent (it would be under fairness rather than fare calculation).