It sounds like you are getting ripped off, unless you were a government worker who didn’t have to pay the full amount of SS taxes in the first place. If you paid the full nut during your working years but are not getting the full SS benefit, that’s just wrong.
So, the full amount ~ did you ever check out how many years you have to work in covered work to get to that point? Check out the facts at: http://ssa.gov/pubs/10072.html ~ I believe that it’s still 40 credits, and 10 years minimum. The inequity you are talking about has been there since the system started.