Q: I was sued on a credit card debt. They served me with a summons. What do I do?
A: You need to file a responsive pleading within 30 days. What pleading you file will depend on a number of factors, including specifically what you were sued for and the amount. You could file a demurrer, an answer or a cross complaint.
However, the decision is one that should be made in consultation with an attorney, not by a paralegal, who cannot give you legal advice or by some internet service. You should also consult with an attorney to see if you have a case under state or federal law against the collection agency. Even if you ultimately decide to represent yourself, consultation with an attorney is always a good idea in these situations.