15% discount offered on co-payment not full Test amount

Had a surgeon check a lump on my neck and paid R1200 cash as had tests worths R5000 done to check why I was losing weight. One test from Holmlab using Pathlsb cost R2000. Med aid cover more than 75% of the bill. When I asked if I can get a 15% discount I was initially ignored even though on pension and with a Bond. Then due to technicality only wanted to give me a 15% discount on the co-payment. Extremely expensive in my view and uncaring