Social Security Request, How I Can Fulfill It, and Does It Even Matter?

I’m a retired Illinois teacher, and I’ve just received over $7,000 from Social Security in my checking account. The only email I received from Social is one that said I might be eligible. Then all of a sudden, I received this money, which I welcome, but there was no further information. However, in the original email it stated “If you had any change in your pension amount between January 2022 and December 2023, please provide us with the date of the change and the old and new pension amounts. ” I obtained a letter from the Illinois Retirement System showing the increased amount for those years. But there’s no way I can upload it onto the My Social Security site. The general Social Security rep said on the phone that I have to contact my nearest Social facility, Mt. Prospect, to get a code that I would input in order (no idea where to input it on their site) to upload the letter. But I can’t get anyone on Mt. Prospect’s phone, which has hour long waiting and no call back. I can’t see any way to make an appointment for Mt. Prospect on the Social website, either, although it says I can do so. Do I just show up at Mt. Prospect with the letter? Will it even matter for future Social payments, which are small, since I get a TRS pension? SO frustrating! Thank you for your expertise on Social Security and your help.