Well let's be clear here. The only role of the process server is to serve court papers on a party. They do not represent people in lawsuits. So your beef really isn't with the process server as much as the opposing party. And if you claim service was not proper, you should be looking to reopen your default judgment, not sue the process server.
I agree that suing or pressing charges against the process server is not the most effective course of action. What you should try to do is have the default judgment vacated and have the case heard on the merits. There are a number of elements that you must meet in order to vacate the default judgment, however courts are typically open to having the case heard on the merits instead of allowing the default judgment to stand. Please keep in mind that one of the elements the court looks at in determining if they will allow a vacation of the default judgement is the speed at which you tried to vacate the judgment after receiving notice of its entry. Therefore, moving forward with a motion to vacate in a timely matter is important.
There is potentially a claim that the process server committed perjury through the faulty affidavit which could leave that particular process server criminally liable. However, you're primarily concerned (I assume) with the civil issues, which is how you can recover some kind of damages and avoid this judgment.
Have they obtained a judgment yet? You say they did this "in order to obtain a default judgment," but don't actually say if a judgment has been obtained. Minnesota differs from most states in that you do not NEED to get a judgment to start garnishing in many situations. If they are suing you on the basis of a contract (which is what happens in credit card cases), once they are entitled to a default judgment, they can start to garnish you and put a levy on your bank account(s). It's possible that they started the lawsuit by "serving" you with these documents and then placing a levy against your bank account without filing anything with the Court.
If they actually filed the case, you should be able to find it online. http://pa.courts.state.mn.us/default.aspx If you go to that website, you should be able to find the case information by searching for your name. Otherwise, you may have received a document from the plaintiff that contains the civil filing number, which would look something like: 27-CV-13-#####. You can search that way as well.
If the case has been filed and a default judgment has been granted, it's more straightforward for how you proceed. You would file a motion pursuant to Minnesota Rule of Civil Procedure 60.02 for relief from judgment on the basis that you were never served. If the affidavit of service contains a physical description of the individual allegedly served (something that isn't common for me in Minneapolis), you should have a pretty strong case just on its face. The judge then has the power to grant that motion, which ends the levy/garnishment.
If the case has not been filed, you should send a written answer to the other side. I strongly recommend having some assistance from a local attorney for this. I think your best move is probably a motion to dismiss for failure to serve. You also will want to explore claims related to the FDCPA. From what's in the fact pattern, I don't know if there is a violation in your case or not. Once you send an answer, you shouldn't be "in default" anymore and the levy should be lifted and the garnishment should stop.
This response is not intended to create an attorney-client privilege and is based only on the facts which have been presented on this forum. www.dreweslaw.com