Refusing to give my Original certificate and Relieving letter.

Details about the Issue: On 01 June 2022, I joined APP innovation technologies PVT LTD for the role of "Business Analyst." During the joining process, they requested my 10th marksheet for verification. After some time, they asked me to sign a bond paper. The bond was not on stamp paper, but rather on white paper, stating that if I left before the bond period of 2 years, I would have to pay a sum of 1 lakh rupees. However, there was no mention of not returning the certificates if the bond was broken. Since I was fresh out of college, I signed the bond without much consideration. After that, I started working as a Business Analyst. The company had a policy of providing a salary hike every 6 months. When I joined, my first salary was 18,000 rupees. I was one of the employees who put in full effort on my projects, and everyone on the top floor recognized it. After 6 months, I received a raise of 7,500 rupees, making my salary 25,000 rupees. After PF deduction, my take-home salary was 21,500 rupees. I requested a higher increase, as I had been working diligently on the project, leading the team of developers, and managing clients. They informed me that I would receive a larger raise during the next hike, so I agreed and continued working. After another 6 months (12 months in total), on 27 June 2023, I was called inside the office to speak with the owner's wife, who was the head of HR. This time, I provided them with evidence of my work, such as my performance review report and analyzed notes. Even after reviewing my work, they only offered the same 7,500 rupees raise. I was not satisfied, so I expressed my expectation of at least 10,000 rupees. If I couldn't get 10,000 rupees, I stated that I would like to resign. They asked for my final decision, and I requested some time to think. However, they refused and eventually told me to go home. I sent them my resignation letter, stating my willingness to serve the notice period. In the letter, I also inquired about when I could receive my 10th marksheet and experience certificate. They informed me that I needed to pay the bond amount of 1 lakh rupees, and they also withheld my last month's salary. Now, they are asking for 50,000 rupees, and only then they are willing to provide my certificates. What should I do Now? Can you guys advise me? What should I do next? Please help me out.