[Resolved]  novelty store,goregaon east,near railway station — charging me additional if i use credit card at their shop

Address: Mumbai Suburban, Maharashtra

I shop for a portable harddisk,then when i wanted to pay bill through credit card,he said that he will be charging 1.5 percent extra of the total bill,i asked him,do you have any letter that you would be charging legally to every customer,than he said,thats none of your business and talked rudely and told bad words about government stating who follows the rule..i wanted to know,is he doing right?
is there any such legal rule.