Change in Notice period after joining

I’m working in MNC for past 4 years and till now the notice period was 30 days . Recently we received an email stating the notice period is changed from 30 days to 90 days . I had a word with manager stating I do not accept this cause as it is a very stringent policy change . The HR and my manger said a company has a right to change polices . As per terms of employment given to us when joining the company there is line mention-(Your employment for Solutions Private Limited will be governed by Company's policies, as modified, from time to time and at Company’s sole discretion, upon notice to you. The terms and conditions contained herein ("Terms of Employment") must be read in conjunction with Company policies. Any policy infraction will amount to breach of your terms of employment and may lead to termination of your services. These Terms of Employment and policies shall be subject to modifications, from time to time, upon notice to you. ) . This point is given as a heading and below along with other points The point for notice period is (10.3. (a) If your career level is 8 to 13 and you are assigned/deployed to Contact Center business deal: You may at any time terminate your employment by giving the Company thirty (30) calendar days prior written notice. Upon you providing such notice, approval of any request for early release and/or any kind of waiver will be granted at the sole discretion of the Company and will be subject to terms and conditions of the Company, including and not limiting to the recovery in lieu of notice period not served.) Can you please advise what action I can take . My manager said that company has right to change the policy . Please advise if my company can change the policy for existing employees or not