Is there any condition to claim refund of unutilised ITC

Yes, and the condition is that supplier of goods or services has not – availed drawback in respect of CGST or claimed refund of IGST paid on such supplies. In other words, no refund of input tax credit shall be allowed if the supplier of goods or services avails drawback in respect of CGST or claims refund of IGST paid on such supplies.

(ICAI FAQ PUBLICATIONS 06-09-2017 REFUNDS : FAQ NO. 12)