1. A PIL is not a pill for every ill. If Kotak had traded through your account without any order placed by you and you suffered loss as a consequence thereof then you should have sued Kotak for damages. It is not understandable how arbitration could be necessarily invoked when Kotak had acted without authority. Be that as it may, you can challenge the arbitration award in the court.
2. It seems to me that you had a better legal recourse than going for arbitration, but it has been waived by you.
3. You did not have to appear personally in the arbitration proceedings if you were represented by your lawyer.
4. The contractual obligations which have already come into existence are not wiped out due to the deal.
5. Do not rush into filing a PIL. You may have a better legal recourse available to you depending on the outcome of the arbitration proceedings, the right impaired and the consequent damage. Consult your lawyer.