It should be covered abd the remap has nothing to do with the failure of the alternator. Did you tell them your vehicle was remapped? I would suggest you go back let them know that UK Audi now cover this under an extended 7 year warranty and unlimited mileage. If they still say no then I would escalate this to UK Audi and then follow small claims court. The remap has nothing to do with the alternator failure. Its a defect on that part.