I rely on my avian vet for many things, but not when it comes to diet. Well that is not entirely true, I do listen very closely and then discuss it with them, just the same as I do with my own doctor. I have several avian medical texts and while they do cover nutrition it is only very briefly.
At one point in development of pellets, it was claimed by the manufacturer that they were a complete diet for our parrots and the vets went along with this and today still sell which ever brand that they prefer or who gives them the largest profit margin. But it has been proven that our birds really do need to have fresh fruits and vegetables in their diet. It is now recommended that parrots eat at least 30% of their diet in the form of fresh fruits and vegetables, Pellets are recommended to not exceed 30 to 50% of a parrots diet depending on the species of the parrot.
Just like with human doctors, not all vets are equal, some are much better than others, some are " old school" and have not kept up on the latest developments in bird nutrition and others are sometimes too much on the " cutting edge".
I do not feed my birds pellets and after discussing what I feed my birds and going over the values in the blood tests done on my birds, my vet is very pleased with what my birds are eating. This does not mean that pellets do not have a place in parrot nutrition, they do as they are one way to insure that your bird get a certain minimum level of nutrition.
The best way to get your bird to eat the frits and vegetables that it needs is to add them to your own diet and then to share them with your bird as well as to always have some prepared and in their food dish. This does take some time and I consider it to be an ongoing process. The reason that your bird does not eat these foods is that it was not taught to eat them when they should have been taught about them and as a result it does not recognize them as food. I can go into more depth about how to teach your bird to eat these foods if you need me to.