Not paying a Dr visit

Today we received a call from the Dr office to inform us that we need to pay them R400 because Discovery will not pay as we are part of the cde program for diabetes and need to go to the cde clinic. We did the cde option because we ALWAYS have problems when we get her medication that discovery doesn't pay, so that part is sorted, we go to Dr Janie van den Berg as she is a Endocrinologist (diabetes) and a physician, my wife is pregnant and needs to make sure her sugar is under control as well as her general health is good, so now Discovery doesn't pay this? Its a normal Dr visit so why is there a problem, I pay one massive amount pm for membership but get nailed from you still so why am I part of you? This is shocking and I will make sure that everyone I know how Discovery is taking money and not providing any service! I pay you to take care of this so why must I pay even more for a visit that I already pay for in my membership so you are taking more and making excuses not pay for anything. I will be cancelling my membership as I have endless fights and issues with you and have never had a good service/experience. Fix this and pay the Dr as that is what I signed up for