Not refunded total amount on order cancelled.

When I cancel my order flifkart deducted 10 rupees as a name of platform fee from the total amount without any information, at the order page their is also no information about that The platform fee was not refundable. When I talk to customer care representative, Mr mujahit on call and he dined to return my 10 rupees. Total amount to refund 673 but flipkart refund only 663.