Cleartrip — credit shell utilisation of cancelled flight trip id[protected]

My flight for 28th may was cancelled by indigo and they provided me credit shell for that cancellation. As i booked the ticket on cleartrip i tried to utilise my credit shell on cleartrip for my new booking but i am not able to use it as when i am putting the pnr of credit shell of cancelled flight cleartrip is showing pnr invalid. I have mailed cleartrip regarding this 36 hours before but my issue is ye not resolved. I am in urgent need of flight booking but still cleartrip is taking too long.