Worst service ever!!!!!!!!!!!!

My account has not been sorted out since February. My doctor is a network dr. And everytime may claim gets rejected because Momentum states that it is not a network Dr. I spoke to many different consultant about my claim and they all confirmed that it is a network doctor. They even sended the claim back to the department to fix it. The one consultants even said that my payment is sorted out. This morning I founded out that it was rejected again because it is not a network Dr. What is wrong with Momentum???? It is a network GP!!! Worst service ever!!!