Company is asking money for not serving full notice period

I am a start performer at my job but I had to put down my papers in my last organisation during covid period as my marriage for fixed. My contract stated 3 months resignation period but my wedding was arranged and i sincerely informed my employer that I won’t hence be able to serve the same. After serving about one month of my notice and still going back and forth i got covid and my family moved me from home to my village for recovery. (I have my aadhar linked tests/ medical for this). While i was in quarantine, the HR called me one fine day and said they are sending someone to my house to pick up my office sanctioned laptop - which my parents handed them over and they closed my email ID. There on their Finance has been sending me mails to pay them for pending 2 months notice period which i did not serve. I didn’t ask/get any salary for same either. In my employment contract they also state that if person is absconding without notice for more than 10 days then it’s considered as termination of contract. So they could have simply revoked same as i was off for more than 2 weeks. But its been 5 months and their finances team keeps calling and screaming at me. I have only 3 years of work ex. And I didn’t even know till recently that I could have gotten changes done or asked at least at time of signing contract to get notice period reduced. My senior has asked me to take legal advise hence on this matter. The company has past record of misbehaving and pressuring junior employees to do such things. They have sent back a whole finance working sheet for deduction as well projecting taxes against salary i have not been paid. Please help advise how i can respond to them to stop threatening / misbehaving with me? Also i missed their mail from finance which stated at bottom “In the event you seek any clarifications, you are required to revert within 10 days of receipt of this email failing which it shall be deemed that you have agreed, accepted and acknowledged all the above said and all our obligations towards the subject matter stands discharged.” Is this ethical for them to do? They have concluded that i have agreed to this mail about giving them money since I didn’t see this mail in 10 days time. I feel as if they have trapped me in this situation. Please help?