All consulates are authorized to consider exceptional circumstances such as @D-R-J mentioned.
Immigrant Visa I-130 Petitions - U.S. Embassy & Consulates in the United Kingdom (usembassy.gov)
If you are a U.S. citizen, the Department of State may accept a petition from you if you are filing for your immediate relative (spouse, unmarried child under the age of 21, or parent (if you are 21 years of age or older) at a U.S. embassy or consulate in certain limited circumstances, as described in the USCIS Policy Manual, Volume 6, Part B, Chapter 3.
If you have reviewed the exceptional circumstances and believe you qualify, please complete and submit this contact form for consideration.
If you qualify for exceptional circumstances, make sure you don't file an I-130 with USCIS before allowing the consulate to evaluate the situation.