naive

im a legal resident of this country but unfortunately i still dont know alot about the american laws. they called my parents in-laws' business looking for me and told them that they're building up a case against me and that i needed to call them immediately. when i found out about it i called them right away and willing to pay it off since i did recognize HSbank. i had that credit card when i was a teen & gotten into collections. but they wouldnt accept any kinds of payments whether a bank wire since i only have a savings acct, nor money order or money gram. they told me they're not collection agencies but a firm and will only accept a check and if not they file a lawsuit against me to take me to court and that i will end up paying quite a whole lot more. so here i was very naive & stricken in panicked. so i gave them my social as a confirmation that i will pay them. but then a wise friend of mine looked up their site & found a whole lot of complainers against these brady&carso company that they're possibly scammers. im worried because they have my social number and that even until these days they still call me and threatens me to pay them immediately. what should i do pls help