Keeping my pet hostage

I would just like to say that we have had the worst experience with Ashburne Vet. Our cat had a puncture in his one eye from another cats claw and it looked bad, so my brother took him to Ashburne to check that it was okay. When he got there they cleaned him up and say he would have to stay overnight and my brother had to pay a R4000 deposit. My dad went into the Vet when he got back from being in JHB to visit our cat Leo and he was not well they had given him medication that made him nauseous and said he had an infection. The next day, they sent my dad a message that Leo was ready to be fetched and that the outstanding bill was R9000+. Turns out they operated on our cat without phoning us and asking for our consent. Ashburne Vet are now keeping my precious cat hostage, demanding payment from us for a procedure we didn't even consent to. I am absolutely disgusted by the way they has treated my dad, and I really wonder about their integrity. I will not rest until my cat is safely home and Ashburne are found guilty of poor practice!