Relieving letter and buy out

Hello, Currently I am in notice period. Due to personal reasons I am not able to serve full 3 months notice period and company is forcing me to serve 3 months notice period. I am not able to serve 50 days out of total 90 days. I am ready to pay the compensation to company for the 50 days for not serving notice period. But company HR response is " I am ready to accept the compensation for the days not serving notice period and u can leave. The company will decide whether to issue relieving letter or not" In my contract below is mentioned for buyout. "You may also terminate the employment (tender resignation) at any time with prior written notice of not less than 3 months. In the event of your resignation and if requested by you to be relieved earlier, the Company may at its sole discretion accept your resignation and relieve you with immediate effect or at any time during the notice period, provided you agree to pay Notice Period Compensation. Notice Period Compensation (NPC) shall be the pro-rata gross salary for the shortfall of notice period. " Please help me with this issue. Thank you.