Bad experience at Prive Pure veg restaurant, ECR

So I went to Prive veg restaurant yesterday with a couple of people. When we were having lunch, we found a cockroach in the mushroom side dish that we had ordered. The waiters were very unapologetic and seemed like it was a very casual occurrence to them. I had to call up the manager and tell it to him. Any ideas on where I can report such incidents legally? I don't want others to face similar incidents.