College holding original documents

The college or polytechnic cannot retain the original certificates for any reason.

You approach the registrar of the institute or issue a legal notice to the polytechnic demanding the return of your original certificates by paying the dues that you are required to pay.

Please note that the institute cannot compel you to pay the entire term fees and hold back the original certificates as ransom, this is highly illegal, 

You can even approach the director of your State technical education board or AICTE with a complaint 

Yes, college can't  retain original documents of  student for any reason.Issur legal notice and demand your original documents even if college  does not return to you original documents then file complaint before District Consumer Commission  against college and claim your original documents and compensation towards mental and physical agony.