ACS Law Firm Threatening and Fraudlent phone calls Ageles, California

I received a phone call on Monday from a man with a thick Indian accent claiming to be Kevin Foster.  He left me a voicemail telling me that I needed to call him back immediately and that if I didn't he could only say God help and good luck.  When I called him back he was talking over me and wouldn't let me ask any questions.  He kept telling me that I was being sued and had criminal charges filed against me and I was due in court on Tuesday and that if I wanted it to stop I would have to send him $998 immediately and fax him my id and a letter.  He would only tell me that I owed money to an online payday loan under Cash Advance.  He wouldn't tell me who the actual loan was supposedly due to and would not send me any papers proving that I had a loan out.  He had all of my information, including my ss#.  He was very rude and could not answer anything I asked him. 

I told him that I would have to look into this and get back to him.  I called the state prosecutors office and had them check my ss# to see if I had any files against me and they said no, this is just a scam.  I also checked my email with Cash Advance adn they also told me I owe them more money.  These people will not stop calling me!  The phone calls started today at 10am and are still going.  So far they have called me 40 times over the last 8 hrs.  I am going to have to have my phone number changed because apparently no one can take care of these people. 

The phone number he had me call him back at was 209-729-3813.  They also gave me a fax number that had a 686 area code.