Where to send form 843

Hi experts,

In 2021, I was a F1 student but my company still took Social Security tax from me. When I filed tax in 03/2022, I used Sprint Tax and they guided me to send the form 843 to Department of the Treasury, Internal Revenue Service Center, Ogden, UT, 84201-0038. I sent all required documents to that address in 04/2022. UPS showed me the package was delivered 1 week after. I waited for almost 2 years until 01/2024 and didn't hear anything from them.

I called them in 01/2024 and a staff confirmed that they have never created any case for me, it means they might not receive it ever. She guided me to send the package again to the same address. We both checked in the 2022 Publication 519 (the latest version in 01/2024) and it showed exactly that address. I sent the package the second time, USPS confirmed the packaged was delivered 5 days after. I waited for 45 days, I called them again and again the staff said no case is created yet. She asked me to wait more and also she confirmed I should send the package to Department of the Treasury, Internal Revenue Service Center, Ogden, UT, eight four two zero one-zero zero zero two, just because I am a California resident. I submitted the package the third time in 03/2024 and USPS delivered it 3 days after. Now I have to continue to wait.

My questions are:

- Can you please let me know which is the correct address to submit form 843? I always live in CA and the form 843 is for 2021 tax year. (I know that for the 2023 tax year, they have a new instruction to send the form to Austin, TX).

- In the worst case if I can't get my money back (Social Security tax took by a mistake of the company), any benefits for me when I paid that tax earlier than I had to.

Thank you very much!