None of what you describe in normal. At least on my bench. I do an evaluation and then send a quote. You approve the work gets done. If in the course of tearing down the regs I discover another issue I stop, send a message, and get your approval. Unless it is something really small.
Your mouthpiece for example. I have one set of regs here that when I took the mouthpiece off I discovered a tear under the zip tie. Standard factory mouthpiece. These regs happen to be for someone overseas. Well I missed it in the eval so I replaced it. Charge for that - 0.00. Mouthpieces are cheap. I did note it when I sent the invoice for payment.
Your LP hose? What was wrong with it? Did you get the old one back? On these same regs I discovered a cracked and split 6" HP hose. That was in the original eval and the service price quoted included it. I would not have replaced it without his OK.
After your experience last time why did you take it back to this shop?
No extra work should have been done without your OK. Even if they refused to go through with the service if there were legit things wrong that you did not approve. For example if I see a bad hose I am going to get your ok to replace it and I will send pics or show you the hose. If you refuse to have the hose replaced then I may refuse to service the reg if I think you will dive it with a bad hose. But you will know this before I even start the work.
I advise people to not just take a reg in and say "here, needs an annual." Have the tech do an evaluation and test. It may not need a rebuild. Just a good cleaning and adjustment. Get an estimate before they do the work and ask why this or that needs done. And get your old parts back.
That they replaced a battery after you specifically told them not to would tell me that this is the wrong place to take anything.
Guess that's why I get people sending me regs from all over. These ones I was just talking about. They are on their way back tomorrow. To my customer in Okinawa, Japan.
I'm with Jim on this. Nothing should've been done that you didn't authorize, unless there was something in the agreement you signed that said, if it was less than $5 for example. And after the battery replacement after explicitly requesting that it not be done, I'd look for another shop to perform my services.