If you have a complaint against a scheduled bank, you can lodge it with the concerned bank in writing in a specific complaint register provided at the branches. Ask for a receipt of your complaint. The details of the official receiving your complaint may be specifically sought.
If the bank fails to respond within 30 days, you can lodge a complaint with the Banking Ombudsman. Remember that complaints pending in any other judicial forum will not be entertained by the Ombudsman. No fee is levied by the Ombudsman's office for resolving the customer's complaint. A unique complaint identification number will be given to you for tracking purpose. The RBI website has a Banking Ombudsmen list, along with the contact details.
Complaints are to be addressed to the Ombudsman within whose jurisdiction the branch or office of the bank complained against is located. Complaints can be lodged simply by writing on a plain paper or online at www.bankingombudsman.rbi.org.in or by sending an email to the Ombudsman. The complaint forms are available at all bank branches also.
The complaint can also be lodged by your authorised representative (other than a lawyer) or by a consumer association/forum acting on your behalf. If you are unhappy with the Ombudsman's decision, you can appeal to the Appellate Authority in the RBI.
Source: Economic Times