ABN AMRO Home Loans — not reducing interest rates

Hi,
Four years back I has taken a home loan from ABN AMRO bank at the ten floating rate of 7.75%. The rate was suppossed to be fixed for five years and after 5 years the floating rate prevailing at the time will be applicable. We hadnt done the full disbursement of the loan amount, and whenever the lending rates changed (read increased), a weighted average was applicable for us. Currently the weighted average intetest rate for my loan is 10.42%. Recently there has been a series of reduction of lending rates by the RBI. But ABN Amro bank is not passing on this advantage to us. They are giving various excuses like the loan is fixed for five years, etc. And when we questioned them on the weighted average rate that was being charged all these years they are now coming up with the excuse that they no longer have fixed loans so the reduction in rates is not applicable to us.
Is there anybody else facing this similar issue? Can I complain to anybody about their misbehaviours?
Please let me know.

Thanks.