Its in their interest that they issue the relieving order. Send them a mail on your last working day. Also casually mention to them that there is a recent court order stating that salary needs to be paid till the date relieving order issued. I do not have the case lawviff hand. But, there is a case in MP where a court has stated that in case the relieving order is not issued on or before the last working day, then the company is liable to pay till the date it is issues. Just verbally mention to them.