incompetent vets

Took my Bulldog to the Glens Vet Hospital got bringing up. The vet diagnosed him with brochirtis . The dog got worst rapidly that he eventually stopped eating all together phoned on a sunday to enquire they promised to phone me back never did, decided to take my dog to another vet which diagnosed him with a tomar in the stomach and had to put my dog down. How can the diagnoses be so wrong and so extreme