If u have ac in same bank they will not ask anything. Just call cc
Some bank like sbi gives this option in app. Some require cancelled cheque. If u dont have ac then its better to mail with cancelled cheque. It will be faster
Got refund from ICICI to a non icici savings account.
Mailed them and they asked me the account details and a picture of cancelled cheque.
Got the refund within 48 hours.
You can escalate that over Twitter to speed up the process
Kuch bank cancelled cheque mangte hain and kuch nhi bhi