Social Security Questions? Ask a Social Security Expert
Good afternoon. I'm PDtax, and will assist.
There are a number of ways to get the information you are looking for. I would start with access to your social security account, now available online as MySocialSecurity. http://www.ssa.gov/myaccount/ is a link to signing up for access online.
Chances are, the lien would have been identified. It should be noted that there are very few liens allowed against social security benefits, so I might focus my search on unpaid Federal income taxes (Form 1040) or other such tax debts (some states tax debts, child support, student loans, and some other debts).
Another simple source might be your credit report. Collection against social security typically requires the issuance of a tax lien/levy (Federal) or tax warrant or similar name (That's what my home state, NY, calls their lien). I suspect that the exact amount collected from social security shows up as paid on your credit report.
I also suspect that social security may have been respecting your privacy by not discussing your file with your representative. It can be difficult these days to get information released, especially over the phone. You might consider a visit to a Social Security office directly, where you can prove your identity and access your account with a SSA employee providing assistance.
There is normally a statement sent to you from SSA that explains the levy and the name of the creditor. That will be available at the SSA office when you go.
Thanks for asking at Just Answer. Positive feedback is appreciated. I'm PDtax.