請教: REF 要求的材料不象是我的case. 怎麽辦?

Just received REF letter and ask for I-864A. It says I used an older version. But I only have one sponsor I-864 and one co-sponsor I-864.

Do they didn't read my file correctly or they messed up my case with someone else? How do I answer this REF? Can I go to Infopass to ask?

I'm kind of confused about the choices at the website: should I choose "You need Service on a case that has already been filed", and then "Case Processing Appointment - If you received a notice to go to your local office for further case processing."? or the "You need information or other services"?

Please help! I worried if I didn't reply as they expected, they will deny my case.