Ola Cabs / Ani Technologies — driver has collected extra (rs. 3257) money

I had booked a cab on 24th of august at 9 pm for my friend from bangalore airport to moodbidri (Manglore). I had to book as he cudnt get thru a cab n had arrived from malaysia. They reached at 4.40 am on 25th of august. Agter reaching driver asked him to pay rs. 15000 though my friend had to pay 9043 (Bill amount) + 700 (Toll charges). N after arguing, finally he took him rs. 13000 from my friend.
I complained to ola several times. N after 5 days they replied saying that we must complain at same time of paying the amount. It was 4.40. Am n my friend didn't call me up to inform as i was under medication for a month n i had told him not to call me up as i had severe eye problem.
When i contacted the driver he says, he has nothing to do with the ola n he will not pay back that money.
Driver has taken rs. 3257 extra saying that he has to come back to bangalore without any passenger. I had booked the cab for one way.