How to proceed further?

My Dad is 54 yes old. Last year 01/09/2023 he took up a non teaching job in a college. During onboarding, he signed a legal contract stating to work for 3 years and 1 year in probation, in case if one has resigned before the contract. One has to pay 90,000 for 3 months notice and 90,000 for breaking the bond. In total 1,80,000 should be paid and the institution has withhold my dad's Original degree certificates. The job included more physical work which was not mentioned in the appointment order. My dad could no longer continue. My dad has asked his superior (head) to change his role due to health constraints twice but they did not change it and He even asked the HR to change the role but the HR did not change as well and after 8 months. He could not longer continue, so he resigned and gave the resignation letter to his superior and HR. In the resignation letter, my dad mentioned it as resignation due to health issue. And he wasn't able to give the said 3 months notice but he gave 1 month notice and after leaving the institution he got an mail saying termination of resignation and must pay 1,80,000 My dad mailed them back politely stating the reason for resignation was because health constraints. Now my dad has got an legal notice stating to pay 1,80,000. What to do now? Are legal contracts legally enforceable? How to proceed?