It is important that you pursue this and repair the problem.
Have your dealer remove the lower motor covers and visually inspect the control cables, installation and adjustment.
The control cables should be disconnected from the engine to test for proper operation of the control and cables.
The engine can also be shifted by hand to verify proper operation while the control cables are disconnected.
The boat and engine wiring harness must be connected in a specific manner on your engine. If the harness is not routed properly it could interfere with the operation of the shift or throttle.