Do I have the right to choose between serving notice period and pay salary when I put my resignation

The following terms is included in the letter of appointment: " 1. Your services will be terminable by written notice of three months on either side or salary in lieu thereof, the company retaining the right to pay salary in lieu of notice period. 2. The company considers that irreperable harm, not capable of completion in monetory terms, would be caused to the company in case you were to a. take up employement with another person during the term of your employment with lthe company b. solicit employement, in any capacity including employement as an independent contractor, employee or consultant with any person who is a supplier, customer or compititor of the Company. c. Wrongfully terminate your employmemt with the company. " I have resigned in the beginning of August and mentioned in mail that I want releiving by last week of September. I am willing to pay salary in lieu of notice period. The Company HR is refusing to accept and asking me to serve the notice period in full. He is saying failing to do so will make me abandon the position and he will not issue relieving letter and experience certificate as well as not settle my full and final. Is he legally correct? What are my options in this case? Do I have the right to choose between serving the notice period or paying salary in lieu thereof? I have cited professional and personal (medical) reasons for early reliving. I am not in a position to serve the notice period beyond September NB: I have 40 days of Privilage leave in balance. Pls advice