charge more money than mrp

Location/place: jaunpur

Name of company/service: shyam general store, near VBS Purvanchal University,jaunpur

sir,
i purchase a 2L colddrink of sprite on 22-8-12 having mrp 65 rupees but the shopkeeper charge 70 rupees and i have a bill given by him.when i said why are you charge more money than mrp he told that its a freezing charge.
so kindly take strict action towards the shopkeeper for extra charge than mrp