Anna University — original certificates got by a college and blackmailing

When I gone to visit and take information about Apollo college of engineering they
got all my original certificates to see and give but they suddenly stappled all the
Certificates and kept with them and they are now blackmailing to join their college or to pay one year of college fees to get my original certificates back.We have tried in all the ways to get the certificates. We have requested and we even fighted but they are not ready to give certificates.