Just reverting back to the original topic and my own experience of dealing with SS in a local SS office in Santa Fe New Mexico vs SS in Baltimore vs the FBU in London.
When preparing for my future retirement benefit application for my SS back in 2017 I reviewed my Social Security earnings record (at the time I had 9 years of income from 1986 to 1994) and I noted that there was an error in 1993 whereby my earnings were significantly under recorded - although my Federal Tax Return recorded the correct amount.
I did some work in New Mexico back in 2017 (so that I could get to the magical 40 SS credits) and while I was there visited the local SS office to try and resolve it - a total waste of time - they weren't interested and said to wait until I apply for retirement benefits.
I followed up with multiple letters to the international unit in Baltimore - and drew a total blank - never even received an acknowledgement. As it was so long ago that the error occured, I thought I may be time barred and that it was just too difficult for them - but it was their error and not mine.
Finally, when applying for benefits with the FBU in London a couple of years ago I asked them if they could help - they were super helpful - I was able to supply them with my W-2's from 1993 and my federal tax return from the same year (what an anorak I am, I know for keeping them
) - FBU resolved it within just a few days and my earnings record was corrected - it made a difference (with my wife's pension also) of circa $45 per month - not to be sniffed at for all the aggravation.