Do I have any recourse to this? Why should I pay for the bank's mistake it is not my fault that the incorrectly calculated the EMI. Moreover, the bank informed me of their error in 2015.
You may ask the bank to furnish the EMI calculation and also verify the repayment details and confirm if there are any mistake in calculation of EMI by the bank and whether you are liable for the same.
Since you have not done any mistake and had been very sincere in the repayment also that you have paid the entire loan amount with the interest thereon, you should not accept the liability and should make representation to the higher office giving details and seek their intervention to and discretion to waive the excess amount now demanded.
If they do not agree or you dont get any proper response or the relief is not in sight, you may approach banking ombudsman for redressal of your grievance.
If your grievances are still not redressed, you may approach consumer forum seeking compensation for the mental stress caused by the bankers due to their wrong calculations and attitude to the customers which amounts to deficiency of service and to direct the bank to waive the excess amount now demanded.
Consult a lawyer and discuss the issue in detail before you initiate any legal action other than approaching bank higher official seeking to waive the demanded excess amount