State Bank Of India [SBI] — home loan interest rate

Ref homeloan account[protected] from sbi coonoor iam a retired defence officer who availed this above homeloan from sbi coonoor in 2012. Ihave been paying the emi against the loan without any default. Recently i discovered that the bank is charging me 9.40 percent intrest whereas theprevalent rates are much lower. I need this corrective action to be initiated retrospctive from the effective date of lower intrest application.