Dischem overcharges when paying by medical aid card

Dischem has overcharged me on an immune system supporter. Their Airmune 30's price is R182.95 but it's now on promotion for R166.95. On the 25th August I was charged R223.78 using Discovery medical aid, that's R56.83 extra of which isn't levy. I called the pharmacy on Sunday 26th they said that's what Discovery medical aid charges. I called Discovery on 27th they say no they don't put prices for Dischem. I went back to Dischem but they are adament that is a Discovery's price. Kim from Discovery says they only pay for what Dischem claims all the money claimed goes to the pharmacy. Dischem is taking advantage of medical aid funds. Unfortunately I saw this only when I came home seeing their promotional pamphlet that I was overcharged. Does this mean we should we pay cash to avert these kind of funds abuses?