Original marksheet submitted by company

Hello, I signed affidavit with company according to which i need to join that company on xyz date amd need to work atleast 6 months otherwise they can take a legal action against me. But now i don't want to join that company, i signed joining documents and at that time they asked for my original documents for verification only. I have receipt of that. Still almost 45 days remaining in my joining and i already inform them that i can't join your organisation. There was one more paper on which it was written that if don't come on xyz date then i need to pay xyz amount. But that was seperate document from affidavit. Now how can i get my documents back Any help is appreciated.