Overpayment

My question is why the SSA is coming after me for an overpayment my mother must have received for me when I was 17 years old back in 2004. I am now 25, graduated from college and working 2 jobs and do not collect any governement assistance, in fact I pay in thousands every year to SS. I have called numerous people at the SS office with no assistance regarding this matter and have been receiving letters that they will hold a garnishment from my employer. I am paying back school deb and needless to say am very upset over this situation. How is this legal when I was a minor at the age of this so-called "overpayment" and never even seen a dime?