sterling and seymour

i received a call from a company called Miller and Clark claiming that the police were going to issue a warrant for check fraud if i did not pay $900 for a loan i defaulted on. i told the woman, Denali, that i do not recall the loan and she called me a liar. she put someone else on the phone who was nicer and he agreed to let me pay only $510. i gave him my bank info and told him i would pay the balance in two weeks. but now i am suspicious because when i call the answering machine says the company is sterling and seymour. when i asked Denali who that was, she said she did not know and it must be another department. i asked for he web site info and she said it was under construction. i have not given the $510 yet but if this is a scam i want time to close my account. please help.