First USA review: Threatening call about serving me with lawsuit.

First received a call from a "process server" a month ago saying they had a lawsuit to serve me and they couldn't contact me to serve. They gave me the phone number of the law firm that was handling the case. I called the number and they recited back my address, soc. sec. no., etc. It was scary. They said I owed First USA Bank about $10,000 and they would settle for $4,000 - otherwise I would have to go to court. They stated that the bank had a very strong case and I would lose and have to pay the entire amount plus legal fees. The money I owe supposedly goes back to 2005.

Today both my mother (looking for me) and I received identical calls from the same people. Now they said that I owed $16,093.00 but would settle for $4,500.00. Here's the thing, I don't remember having ANY credit cards back in 2005. In fact the only credit card I have had I got two years ago. I've lived at this address since 2007. I've never received a letter, phone call, anything about a debt before. The numbers they have called me from are: [protected], [protected], and [protected] (The lawyer).