Cat incorrectly diagnosed

My daughter's much loved three year old cat was booked into Keringa Kennels on the first of April 2016, prior to being relocated to Brisbane ,Australia. On Monday the tenth,the kennel manager felt that she had lost her appetite a little and suspected a painful mouth or tooth. He referred her to the Grand Cental Veterinary Clinic. My husband then received a phone call from the vet on Tuesday the twelfth to inform him that the cat definitely had feline leukemia and should be euthanized within 24 hours. This diagnosis and recommendation was subsequently confirmed by a second vet from Grand Central. They had done further tests, not marked urgent, as they were completely sure of their diagnosis. They then returned the cat to Keringa. We went to collect her and found her in seemingly good health. This was subsequently confirmed by two other vets and further blood tests showed that she did not have leukemia. Our family vet feels that she exhibits no signs of illness. We are finding that she is eating well and behaving normally. I am appalled that Grand Central would so strongly recommend immediate euthanasia of a healthy animal on an unconfirmed diagnosis.