Debonding of Capital goods taken on lease/loan basis

Hi experts...

Ours is an STPI unit, we have taken the Capital goods on lease/loan basis from the financial institution without paying the duty, we have done the bonding in 2006, since the lease period is over we would like debond the same. However Custems people are not allowing to give deprication on the same and their claim is since you are not the owner of capital goods you cant claim the depricaiation. They want us to pay the duty on the original value along with the interest.. Please advise on the same.