For customers who have applied for postpaid service, the registered person can bring the original address proof and visit any retail shop in person to submit it to complete the application and avoid service disruption.
Note that the address proof must be a document issued within the last three months from the application date, and it must have the issue date and the name of the issuing organization on it. The recipient's name must also exactly match the name on your identity document.

Please refer to the below link for retail shop details,
https://www.cuniq.com/global/contact-us/Storeaddress