90k LOSS because of HDFC. Shit forex rates.

HDFC bank gave me such poor forex rate on transferring 50k USD, that I lost around 90k INR. This is in comparison to market USD rate. HDFC reps have been nothing but totally incompetent and shit. Bear in mind this was the rate given after a 'special rate approval' and the employee has ever since denied to give any guarantee of future rates or anything. I want my loss compensated in any way or form and not rely on future transactions for this loss recovery. 90K IS NOT a small amount and I won't spare 1 job if that's for me to bear this loss. The problem though, is ,banks have the right to set their own rates when it comes to forex thus the ability to exploit someone insanely, legally. So legally, they are all good. How to deal with this? Should I file a complaint with RBI? Does that stand any ground? Moreover, I am only furious because I def have people in contacts who get better rates, such as only 20-30 paise diff. I got 1 rupee 30 paisa diff.