A better analogy would be going to a prostitute and insisting on a condom, but then the prostitute pokes some holes in it and becomes pregnant "because you seemed lonely so I thought a child might be best for you". That would be a case of requesting one service (protected sex not resulting in pregnancy) but getting an undesirable one (unprotected sex resulting in pregnancy) solely because the service professional disagreed with "what's in the best interest of the client in the view of the [prostitute]". Which, to put it mildly, is not what you paid for. :-)
If a hired professional disagrees with a course of action that a customer has explicitly requested, the appropriate action is to decline to enter into a professional services arrangement, or break an existing one. Not just go ahead with whatever you wanted to do anyway because you think its better.
Not a better analogy. The same analogy. It's a counterpart to the unwanted sex change from the Doctor. (From what I've read, it's certain that an unasked for sex change was performed by some doctors on some infants.)
That is highly contextual. A coworker of mine called that the "Physician <-> Prostitute Spectrum." Certain service providers will pretty much do whatever you pay them to. Other service providers will filter their request through their expert knowledge. This also depends on the nature of the request, of course. It's not like a Doctor is going to give you a sex change you didn't ask for, if things are working correctly.
Whether to plead guilty should be up to the client, unless they aren't competent.