Ola — excess charge & fraud done to me.

I booked a olacab from terminal 1 igi airport new delhi to noida thru my mobile app. Driver of the ola cab asked me the otp code and started the ride. Total fare it showed on the app at the time of booking is 768 rs and after applying the promo code the amount reduced to 668rs. To my utter shock the bill which i got after ride complete id 3194 rs. And when i checked ny mobile app the ride was showing as cancelled but the cab driver showed me bill on his mobile. I am still in shock how did this happened? When i called ola support they refused to help me and said that as the ride is cancelled in the app then we cannot do anything from our side. The cab no is:dl1zc 6892.