Dog food Aggression...help?

My friend has a 4 year old red border collie mix. He is 4 years old and a boy. He is very friendly and social however, he has a major food aggression issue. He reacts very aggressively, with full aggression. They thought they were fixing his problem by taking his food away and yelling and chastising him. Its gotten worse. Its his only issue. What can they do to help him?