Amendment of core field

My client had applied for adding a new Additional Place of Business. The tax officer raised a query which the applicant somehow failed to reply. Now, he wants to resubmit the application but portal is not allowing stating that another application is pending for order. But the tax officer is saying that no application with the particular ARN is pending with him. When I raised a ticket with the grievance cell, they replied that given ARN is invalid. What should be done now? How can a fresh amendment application be filed?