After the acquisition of Symantec by Broadcom, the Managed Security Services department, including Incident Response and DeepSight, were acquired by Accenture.
In order to continue taking advantage of your current support contracts, you will need to contact Accenture directly. They can be reached at these numbers:
1 (877) 889-9009 Toll-free from the United States and Canada
+1 (571) 434-5003 Outside the United States and Canada