FRAUD : Authorized Retail store charged more amount then MRP.

I have bought iPhone11 128gb from Unicorn (Ground floor, Indraprastha Corporate, opp. Venus Atlantis Corporate Park, Prahlad Nagar, Ahmedabad, Gujarat 380015) from Rs. 73600/- but later after few months i have checked MRP which was Rs.69900/- how they can charge Rs.3700/- more than MRP written on box.

Please make arrangements for refund or guide me for further complain process.