-Phantom Foot Faulter
Dear Phantom,
According to USTA Comment 18.6, "The receiver or the receiver's partner may call foot faults only when all reasonable efforts such as warming the server and attempting to get an official to the court have failed and the foot faulting is so flagrant as to be clearly perceptible from the receiver's side." Of course, this is in USTA-sanctioned matches and events. Still, your opponent should not have taken points away from you without cautioning you about your alleged foot faults.