Medical billing discripies

Hello Peter I go to Click Pharmacy at Northgate Mall every month to pick up my prescriptions from my dermatologist, one thing that I have picked up is every pharmist seem to have they own price. Two months ago I went and I was billed R430 which was like almost R100 more than the previous when I asked I was told it was due to price increases, today I went and I was not given a slip to see how much was going to be claimed from my medical aid but I was asked to sign for two prices R500 and something and R 99 which I couldnt understand. Please Help I feel Clicks is taking customers for a ride.