GMR Hyderabad International Airport — coca cola; maintaining different prices of same products in different menus

Dear sir/madam,

The coca cola store which is located to the right of arrival gate has been maintaining two different menus with different prices of same products.
I brought a egg puff from the counter which has price rs.30 written in the menu that is displayed on the wall but i was charged rs.35, which is written on a paper and kept at the product.
And when i ask man at the counter he recklessly replied "it is like that only". When i asked him to come to airport authority, he denied and countered by asking me to call the authorities. He also denied to give his store manager/ higher officer.
The concern is not about rs.5 but it is about ethicality and morality and they may be charging more by have higher difference in prices of other products.
Please take the necessary action against him. And, if this is not right place to inform this kind of things let me know where to file a complaint.