Company is not paid salary and PF, can I break the bond aggreement?

My fiance has been employed at a startup company in Bangalore for the past 2 years. When she joined, the company required her to sign a 3.6-year bond agreement and provided her with a 10-lakh rupee undated cheque as a security deposit for the bond. The agreement stated that during the initial 6-month training period, she would receive a 15,000 rupee monthly salary. After that, her salary was supposed to be increased based on her performance. However, the training period was extended to 1 year, and the salary structure mentioned in the bond was different - 4.5 lakhs in the 1st year, 5 lakhs in the 2nd, 6 lakhs in the 3rd, 7 lakhs in the 4th, and 10 lakhs in the 5th year. But the company never paid her the agreed-upon salaries. In fact, they have not paid her a salary for the past 3.5 months. Additionally, they have not deposited her Provident Fund contributions for the past year. When my fiance asked for a copy of the bond agreement and the cheque she had provided, the company refused to share them. Now, she has decided to leave the company, but they are demanding a 10-lakh rupee penalty. Now company is saying we have spent a money for the training but they didn't not given a proper training. They have threatened to file a case against her if she does not pay this amount. My fiance is unsure if this type of bond agreement is even legal. She is seeking help to address this issue.