Has anyone ever been dismissed from the optifast diet by their Dr. for purchasing product elsewhere?

My Dr. had me dismissed from the optifast diet because I had found the shake product for less money than where he wanted me to purchase it from. I was in the middle of my 4th month of full fast,he dumped me as his patient only to be reinstated if I were to purchase 30 days of optifast product from his source. Has this happened to anyone else? Does he have the right to do this to me? I was totally devastated. He suggested the diet to me for health reasons. I went elsewhere for the product to make it more affordable for me to continue with the diet. I wasn't even allowed to explain, he just had me dismissed from the diet. Is it not my right to find the product elsewhere especially if it's for less money? I would like to let others know that this physician obviously was not looking out for me, his patient, he was out for himself,(kickbacks maybe). He had been my regular physician for 3 years and happened to be certified to oversee optifast dieters.