Traumatic tail injuries not covered!!!!

My client brought his dog in with a wound on the tip of her tail. After she was sedated for the tail to be examined, we discovered that the 2 last vertebrae were fractured and there was a laceration on the tip of the tail. The cause of this injury was traumatic. We had to amputate the last two vertebrae from the tip of the tail. Oneplan now refuses to pay out my client as they refuse to see this as an accident although it was. They say tail amputations are covered under general care which is absolutely ridiculous as this was a traumatic event, and tail amputations for cosmetic reasons were outlawed years ago, so why would any vet amputate a tail for general care????