Thank you all for you help. I really appreciate it.
I wrote a very nice, factual 3 page letter and dropped it off to their Office Manager.
She called a couple hours later and was thankful for the feedback. She said they are always looking on how to improve their services. She said they should have asked more questions.
She said she was right there when the Dr. called asking about my cat and heard her discussing with me about what was actually wrong with her and being diagnosed by another vet.
She cut my bill IN HALF !! Yayyyy.
I'm very glad to pay this. I'm so happy.
Thank you everybody for your help and advice.
You all helped me through this stressful time more than you know.