Hari krupa gen stores charging more than mrp

The general store asked me to pay extra for the soft-drinks stating it is a cooling charge. When I denied he refused to sell it. I informed him that I shall complain, he very bravely said- go and complain to anyone you like. We are here always. Infact, this is the case in all the general stores in and around our locality. I would like you to nail such bindas attitude people who do not fear law at all and take stringent action against them so no one dares to challenge a right consumer. I will be more than glad to further my support in this case. I look forward to your response. Best regards, heena bhat