Startup company holding my original certificates illegally

I joined in a startup company recently. I signed a bond of minimum 18 months. (4 months training+6 months probation+8 months). They asked my certificates for verification on 1st day itself. I showed and they took that entire file from me(including originals of SSLC(10th)+Plustwo+Degree+each sem certificates+consolidated+each PG certifivates+Aadhar+Voters ID). I asked to give back my certificates on the same day. But they said"it will take time". I thought they will give it back next day. Due to some family problems I decided to resign after 6 days. (Only 6 days I worked there).There is no other person in charge in Company other than employer. I sent a resignation letter (via email). My boss didnot reply.. But he reset my company email id. I tried to contact him via my email id and phone. Also went to office. But he was not there. He is online to other employees to communicate. I tried many times and only his advocate called me back. He said to contact him for any complaints regarding getting certificate. He also added that Boss went to US and he will come only after 10 days and not to call him in these days. I waited 10 days and after not getting any reply regarding giving back my documents, I contacted advocate and he said they will tell the decision after 2 days. I contacted boss. He is not responding my call. After todays also I ma not getting a reply from boss. So I again contacted advocate and he spoke rude to me for revoking bond and asking certificates. Atlast my boss mailed me today that"My advcate will tell the reply today or tommorw". Today advocate told wait for 1 more week. What I will do?? Do I forced to pay any money to them??