Can you be served papers at your work?

You can be served a t your home or place of business.  Also, if the original creditor sold or assigned the claim then the new creditor can proceed against you; they in effect "step into the shoes" of the original creditor.

There are still defenses that you can assert, however.  I'm providing you with a list; it is specific to New York courts so the statute of limitations and or other dates and the like may differ form your state law, but it will give you a general idea of what to do:  http://www.nedap.org/hotline/defenses.html