How do I know if I'm being sued

I keep getting calls from some company that I don't know. They say that's there's going to be a case on me because of some fraud. The only thing I can think of is that it can be that one day I need a pay day loan. I gave my information and everything. And then the guy said I was approved for the loan. He then said that I would have to put 75 dollars on some pre paid type of card that I bought at 7 eleven. I then gave him the card number and he said that the 75 dollars was just to be sure that I was a valid and responsible person. He then said that I one more step was need that I had already had a loan out for I think 200 something dollars. Which I didn't. He said I need to pay that before they can give me the loan. I said ok I'm going to try to pay that for him to call me back. He did so but I wasn't able to pay that amount. I the. Said to him for get everything. I didn't want to go threw all that trouble. The. He said that they where going to file a case cuz of fraud.