Ola Cabs / Ani Technologies — i am charged extra 21rs. i was shown 29rs but i was charged 50rs

I was traveling by ola auto.
The location was from. Hiranandani estate today enclave to r mall thane. By 9.45pm on 21st august 2017.
I was shown 29rs while i was confirming the booking. So i had booked the auto, but after the travel git completed, i was charged 50rs.
Which was 21rs more than what was actually shown by the company.
The company has shown something different and charged something diffetent