Hidden Charges - All charges are not disclosed by Jeweller

I recently bought gold rings from a renowned jeweler of the city. They charged the rings at a price of 94% purity of metal but the rings I received are of 91.6% purity as mentioned on the hallmark embedded in the rings. Moreover, they charged 15-20% as making charges and Rs. 300 extra as labor charges which were disclosed to me upfront. Since they are cheating the consumers by telling the price of 94% pure metal to be the price of 91.6% pure metal i.e. 2.4% as hidden charges, which they disclose only if someone asks, What can be done in this case? Although they told me the hidden charges when I suspected the discrepancy in the prices and when I asked them to give me the same in written on the bill what all charges they were levying on the jewelry, they simply refused to do so. Is seller liable to disclose all the charges to the customer up front? Can I file a case in consumer forum against this type of cheating?