Star Health And Allied Insurance — regarding insurance renewal

My mother is being insured with star health since 2014. Every year renewal went fine in time and there are no claims made till date. This year due to my onsite travel, i missed to renew by 25th august 2019 but later within two weeks during grace period only i approached star health renewal team asking for porting my father to star health & getting my mothers insurance renewed. I emailed them on 15th sep along with many multiple calls. None replied or answered to my emails & calls. Finally they responded in the month end of sep 2019 and dragged it further and then acknowledged me saying, since grace period of one month also is completed, they cannot renew and asked me to take new policy where again the waiting period starts. This is totally unfair. They didn't respond nor helped me in the grace period for the two weeks and finally ignoring the customer saying helpless. I have looped level 1, 2, 3 departments of star health for the grievance and none helped me. Kindly help in getting my mothers insurance renewed.