Employment Agreement Breach Notice Reply

Hi All, Below is detailed explanation. Employment agreement issue 1. I received a call from a small IT firm and they asked my willingness to join the company, I said no. 2 Nov 2020 2. The HR insisted me multiple time and I agreed to go with virtual interview call. 3. 2 online video interviews were completed, I cleared the interview. 4. HR called me and asked if I want to join, I said no because it's a small organization and I don't feel job security. 5. HR says, the CEO wants to have call with me, I go in call with CEO. 6. CEO create influence and finally convince me to join, I accept their offer. 9th Nov 2020 7. They send a 100 rupee stamped employment agree and ask me to sign. I say I didn't read the agreement to which the HR says to sign it by same day, finally I sign the agreement digitally. 11th Nov 2020 8. I receive the finalized copy of the agreement which has ONLY MY SIGNATURE, their director didn't sign it yet they called it final copy. 11 Nov 2020 9. I research more about the company and found that company is not at all good and current employees have put very negative reviews on online portals. I decide not to join them. I inform the company that I am going for higher studies and hence can't join. 17 Nov 2020 10. They again insist me a lot and again arrange a call with CEO to create influence but this time I say I don't want to join 11. My supposed to be joining date 20 Nov 2020. 12. I join another company on 20 Nov 2020 13. I receive a call from the company that I have breached the employment agreement because I didn't join them and I will have to pay the penalty. 4 Dec 2020 14. They dispatch a legal notice 15 Dec 2020 15. I receive a legal notice demanding money equivalent to my 2 months salary offer in their offer letter to be paid in 7 days 23 Dec 2020 -------- Agreement clause On Pre Joining: Employee must join company by or before the date of joining as specified above. Company reserves the right to change date of joining or accommodate any request from candidate for change in date of joining. If not feasible company reserves the right to revoke the offer letter. After accepting the offer, if the employee does not report to work on the joining date, it will be treated as termination of employment triggered by the employee. Company reserves the right to pursue appropriate course of action as per the employment agreement. Legal Notice It asks for 2 months salary money on ground of recruitment process expenses and reputation damage. My Question Is this agreement valid if I only sign the agreement and in final which they sent me doesn't contain employer seal, sign, date email anything? What should I do now? And how do I respond. Please suggest..