The snag is not with the scheme administrator but the change itself.
Let me explain.
If you get a medical problem, for example a lung complaint. The insurance company will cover you on a continous basis. If the scheme moves to a new vendor say BUPA then they probably will decline existing medical conditions ie your lung problem.
If you then suffer complaint No 2. and then move schemes again you will find that the new insurance company will cover neither the old lung problem OR complaint No2.
The outcome is that you end up with none of your clinical problems being covered by private healthcare. You're *******!