I am so sorry that happened to you
My cat USED to go to the local humane society animal hospital too.........only because when I adopted him......he was too little to get neutered (8 weekds old). They gave me a free neuter certificate.
Anyhow, when I took him.........it went well but I didn't like the place. They were just too overwhelmed and not-friendly.
We have a wonderful lady vet now