change in email id and mbl no

one of my client had registered himself in gst with the help of some consultant, the consultant had registered his email id and mobile no now he is not giving his user id and pwd also which i am unable to change in gst, i made request to central gst dept to change the email id and mbl no so that we can change his user id and pwd department made the request to gstn but the same has not been updated till date plz suggest how the userid and pwd can be changed