Floating rate of interest for home loan by GIC was not given

I took a home loan from GIC in Bhubaneswar in the year 2011 with a floating rate of interest of 12%. However, for the last 3 and half years, there was no change in rate of interest and I continued paying the same rate of interest. I asked them to give me the reason for the same and refund me the amount which has been charged extra from me. However, there is no response from them. My loan account No is – OR0300600100302.