Pretty much agree with what GreenBird said.
As a rule, people do not like change, even good change. No matter how good/nice/kind/effective the new supervisor, they will makes changes--that's what they've been sent to do. And the team is going to resent every single one of those changes. And they will resent the new supervisor, who is also a change. And they may active work to undermine the new supervisor.
You might be able to salvage individual members of the wayward team, if you can split them up and find them jobs elsewhere in the company, where they will work with none of their old team members. But it's taking a risk, because they might be very unhappy about the changes. And they might take that out on their new co-workers, or clients, or the company as a whole.
As for retraining--what would you retrain them in? They probably can do their jobs, if they've gotten away with all this stuff for a while. I'm not sure you can train people to be polite to others. You can tell them to follow company policy, but how do you make them do that when they haven't been for so long? The team has gotten into bad habits, and bad habits are hard to break. And I'm not sure it's the responsibility of the company to work with them on that.