Query

I am working with Icici and i have resigned in dec after which i got a clearance mail stating my last date as 18 march. There was a cash deposit of 1 lakh in my account in old currency during demonetisation period. I was asked for the source of fund and usage of funds by Icici transaction monitoring team of which i had given the explanation and the required documents which they have asked after which there was no further communication seeking further explanation after 18th jan. Now before a week of my relieving date Icici has cancelled my resignation stating that there is investigation going on. I was not given any notice of cancellation. How can they hold my resignation when i have given proper explanation and if that was not justified then why i was not asked about it in earlier january. If they have to cancel the resign then why it was not cancelled in the very beginning of investigation. My HR and my branch staff knew that i have resigned cause of medical issues and a surgery is planned in march. How can they delay my relieving when i have not been at fault. Kindly suggest is there any legal remedy for this cause i have given the source n usage specifically.