If you have furnished your PAN, the bank cannot deduct more than 10.3% as TDS. If no PAN is submitted, only then can the bank deduct TDS @ 20.6%(20% + Education Cess 2% + Secondary & Higher Education Cess @ 1%).

In this situation, what you can do is file your return with the IT Department and claim the Tax already deducted as Refund. Collect Form 16 A from the bank which will give you an idea of how much interest component has been credited to your account and the quantum of Tax Deducted at Source.

On another note, Form 15G can be submitted regardless of the amount of Income tax you have to pay. This form is nothing but a decleration made by you that you will pay the Income Tax as Self Assessment Tax so no TDS may be deducted by the bank.

In your case, assuming there is no income tax liability, the amount of refund will be Rs.20,000 but you will have to file a return. (Last date for filing return for an individual assessee is 31st July)

You can view Form 26AS (Tax credit Statement) here

https://incometaxindiaefiling.gov.in/portal/form26ASInfo.do

It will only be applicable if you ghave furnished your PAN with the bank.