Discovery price not same as shelf price

Beware when you buy OTC items from pharmacies as the shelf price and the amount deducted from your Savings Account may not be the same amount. For example, went to buy Gaviscon from Dis-Chem today. The Shelf price was R78. Once the transaction has been processed, the receipt showed that in fact R118 has been claimed from my MSA. Upon checking with the pharmacy staff, I was informed that this is standard on Discovery Medical Aid claims for certain products - they have their own price. I must say, this leaves a real bitter taste which not even Gaviscon can cure...