Urgent : please help

recently resigned from Capgemini and sent an email on April 30th( u can read my case in my recent post). HR accepted my resignation and informed me that my Last Working Day (LWD) is May 2nd. They gave me one week to return my assets. The day before yesterday, I returned my assets. Today, I received an email from the exit team stating that I need to pay ₹82,000 for an 87-day shortfall in notice period. However, HR did not inform me about the notice period or this payment beforehand. I have emailed HR. What should I do now?