ACS These people keep harrassing me by e-mail. Nationwide

These people keep harrassing me by e-mail.   I used to have some internet as well as store-front payday loans, but I have paid them all off, and do not owe any current ones.  They keep sending these nasty messages to my e-mail stating they are taking me to court and that if I do not pay the settlement amount of $995.00, they will go to court and I will have to pay $4800 plus dollars in court costs, and attorney fees.  This is not the first time they have done this.  they told me they own my social security number.

I do not see how that is possible.  The case number they gave me is M54-323435666, but it does not say anywhere in the e-mail where it is from, and I can only reply to them by-e-mail, I think they are are a scam, but it also states if I don't contact them by e-mail in 48 hours, I will have to got to court, and all they gave me was an e-mail address at a g-mail account.  It does not mention where they are from in the e-mail they sent to me...'