"We are just medical insurance" - Unity Health Elixi health plan

Talk sure is fast to sell products especially when it comes to health and affordable medical aid. I took out the Elixi health plan from them as the medical aid I had at the time did not cover certain privileges and currently i am only with talksure as I need my Chronic meds and can't wait for a period again. It takes almost an addtional R600 per month extra out of my income . I am on their highest plan and nowhere is stipulation that a person must pay in with a normal doctor's visit that is listed with them. As it was admitted to me that prices are discussed before hand and fixed. I have recently been given an outstanding account due to a "short fall in payment received" . And the excuse? "We are just a medical insurance". Any problem i have had with them their first words to me is "We are only a medical insurance". Now my question stand why do you have us using your so called "network doctors" if they, according to the telefonic discussion with the claims department, are overcharging the customers? Why then have an agreement with them in the first place?