You are the Project Manager for XYZ project. The scope of the project has been completed.

I would contact the Sr. Project Manager to get with the Project Sponsor

The scope is done so it has to be treated as a new (Part of the ) Project. I would ask senior management to take it up with the Project Sponsor or ask if I can take it up with her.

3, if not, otherwise4

Option3

Option4

4. As the scope is completed, the project is complete. Additional work should be done as part of a new project.

Since scope is completed so I assume the project has already been baselined, therefore the change should go to change control board for approval.

My answer is choice (3) You should send the request to Change Control Board for approval.

The scope of work completed and Time duration for completion of project is also finish so any new assignment should treat as a new Project even this is an additional work of same project in this case i will ask senior management to take it up as a new Module.

If the scope of work completed before the planned time schedule and contractor not yet demobilize from site, so any new assignment from client should treat as an additional work of same project in this case i will ask senior management to take it up as a new Module and also send a request to change control Board for approval.

Instead of denying to Customer, You should send the request to Change Control Board for approval hence, option "3" is more appropriate here.

Option3. You should send the request to Change Control Board for approval.Because scope only completed. Still customer not accepted the Product. So Project is not completed.