Not giving original documents

I went for the interview through third party and got selected. At the time of offer the third party told me to provide me with the original certificates which I gave them. They told me they are taking it for verification and would return me back after one month of joining that is on 02 June. On 02 May which was my joining date I went for the job and didn’t find suitable for me as my mom who got sick and I need to rush home. So I explained them about it but they told if you don’t wanna work either you have to pay three months notice salary or serve the notice period so I resumed my duty as I didn’t had that much money. So later when I resumed my job on 07 May the senior manager asked me about it so I told him that sometimes when emergency be there I need to head home to my mom so he said it is not suitable for us as he needs that guy over they. They needed a flexible guy so because of my moms conditions I sometime need to heads home early so he told we wont be able to manage that so with some mutual understanding he told he will release me. So after that the third party is not willing to give me my documents and giving me the only option to pay for three months notice period??? What should I do????