unacceptable doctors bill

Went to Netcare (JHB) in September for an emergency and when we arrived home we received a bill, which we were expecting as our medical aid saving is finished. They also called us and advised us of the bill, which we asked is that all and they said yes (We paid the bill). Yesterday received a phone call to say there is another bill you must pay and we explained that we have already paid the bill. On the bill that we received it say absolutely nothing really of what the doctor did it just has amounts on it. This is unacceptable as we have gone to the emergency on plenty of occasions and never received multiple bills and we have had GP, Doctors and even Paediatrician visit us in the emergency and never received a bill for that as this is included in the hospital bill (emergency room) as that is the person who is on stand by. Can you please look into this and have this bill removed...