Returned letter from USCIS at Washington DC

In June wrote to FL and got reply in early Sept from a USCIS lady (named Constance Carter) in washington DC saying I should get response regading my I-485 in 45 days. However, there is no response from USCIS in 60 days. Last week wrote back to this lady. But the my letter was returned back for undelivering. The lady address who is:

Constance Carter, supervisor
Customer Assistance Office
USCIS
US department of Homeland Security
Washington DC 20529

There is no street address in her letter. Anyone contacted her before with success, please list her detailed address here, thanks