Hello,

If you have made an online payment then there will be option to send you a confirmation message again where you will get the reference number. You can try that way. If not then you can visit the nearby branch and ask for updating your passbook and there you will get all the details and you can ask for details to this concerned transaction. They will have the details and they can share the reference number with you.

This are the only way to do. If not you can use the customer care of the bank where you have your account and ask the concerned person regarding solution to the problem.

Hope it helps!