Uber India — overcharged trip and refused to refund difference

I took uber cab on sep 28 from Bangalore city to airport. Total expected fare was ₹540 (which uber claimed to be 640.23) After reaching airport, fare was changed to ₹1049.4. I had to argue with driver on this. Later I paid him and complained to uber . I got response saying fare was 640.23 and balance will be refunded. I received ₹409 as uber credit. So far ok...
I took uber again on oct 3 to travel from Bangalore airport to city. Fare shown was ₹ 651.18. Final amount was supposed to be reduced by amount in my uber credits.. however after reaching destination, same did not happen and driver insisted to pay full 651. Since my phone app also shown same 651 only, I paid full amount to driver. I raised it as complaint to uber. I got response as seen in attached image saying since transaction is done outside uber system, same cannot be refunded. I did not agree to this and again further raised it. Now i received a call from call center. Executive on call agreed to the issue. She offered refund of only ₹ 150 instead of ₹ 409 as per uber policy.

Uber you have faulty software. Instead of fixing the issue with software, you expect us to accept such partial refunds?
I denied to receive partial refund and hence nothing has been credited to my account.