No payment and no notice of change of old plan

Discovery has this thing where if your benefits are depleted you still have 5 doctor's visits that will be covered by them. We have always used the same doctor for years and never had a problem. Suddenly on December 2017, they decide they will not pay my doctor. After allot of phone calls with both the doctor and D4 consultants, they refuse to pay because the doctor has been taken of the Premier Discovery plan. WHO makes this decisions ? Where is the medical board or ombudsman that should protect the public against this kind of racketeering . One moment your covered and the next your not. Why is there fine print plans that the clients are not informed about ? I want this fixed and I want an apology letter for both the doctor and to my wife for the insult. I do not pay peanuts for a husk of a plan. Thank you