Pf clearance

Hello i am abhinay gupta a lifestyle accessory designer by profession. I was working with a firm for 2years. After seeing the amount of my hard work and dedication they sent me to china for more industry exposure but after 2 months I got selected in a college for my master degree and it happened in a short time span so i had to resign from the comapny. I could not do a handover and also could not go back to the comapny for settling accounts. The same day i got mail saying they will release me after paying the expense of my china visit. I haven't signed any leagal documents for assuring them that i would be staying in company for long time. When i was not aware that i am going to get selected in the college in a verbal communication somehow i showed interest that i would work with them for longer duration. So they are saying you made verbal promise to us and if u are leaving then you have to pay that amount. They sent a letter to my college also raising the same issue. I was very clear to them that for further education I am leaving the organization. Somehow my hard work and dedication got zero appreciation. After that they pushed me to pay but i was not ready to pay for the things were not initiated from my side it was their decision to send me to china. I haven't got my releasing certificate, experience certificate. My pf is also on hold i didn't talk to them about releasing it assuming they will not do it. So how can i release my pf without comapny interference.