Am I in the wrong or is my vet in the wrong?

Hello, I am new to reddit but not new to having cats. A few months ago I took in two feral cats that I had been taking care of whilst they were outside for a bout a year. They’re both females and look about to be around 4 years old

Since I already had two female cats in my home (I live with my family) my dad suggested I get their vaccines immediately which I did the very same day. As many of us are aware vets are very expensive and so my dad and I decided to wait on the spay/neuter and only get the necessary vaccines, despite my vet telling us they were not spayed even though we believed them to be cats who previously had owners.

Fast forward to now my dad and I decided we should finally get them spayed and so we went to the exact SAME vet we had previously gone to. Once we got there they did inform us we needed to get their vaccines updated which we agreed to so it came out to being around $220 in total for both cats.

A few hours later my dad receives a call from the vet and they told him that they found out the cats were already spayed but without our consent or knowledge went ahead and ALSO completed an exploratory surgery on both cats to attempt to further locate their ovaries even though they found them in neither.
This resulted in an additional $500 charge. When we went to go pick them up we attempted to get my answers as to why we weren’t informed they were going to complete an additional surgery without our knowledge but they just kept telling us it was necessary despite them already being spayed.

I just don’t think they should have gone ahead with this surgery if they already couldn’t find their ovaries in the initial one, especially since this vet is supposed to be “low-cost” I would think this vet would have more concern towards how much they are charging pet owners based off of what procedures are not necessary. Additionally, every time we brought up that the exact same vet told us both cats were NOT spayed they would claim there’s no way they would have known..but then why give us false information the first time???

They also sent both my cats home with their carriers and cones covered in feces which could have potentially infected their wounds. After this experience I looked at their Yelp reviews (they had a 1.6) and found other very concerning reviews like giving the wrong dosage information to pet owners or flat out lying about test results.

Please let me know if this is a normal occurrence!!!