first check to see if they are a qualified credit reporting agency. They may have told you they will give you a negative report to the credit reporting agencies, but if they are not qaulified, then they can not report you.
if they are not a qualified reporting agency, send a complaint to the FTC for making false threats and harrassing you, Also ask for s signed copy of any contracts you supposedly signed. I real contract requires a signature in front of a bonded notary with an authorised stamp. If it was done over the phone, it could have een anyone claiming to be you.
I have seen a website for SMC that was for sale. They were asking for $50.000.00 to buy the site.
I would like to see SMC try and sue everyone in every state and country that has filed complaints against them or told them to cancel their contracts. With their reputation, I would bet they would not want their business to be investigated, nor would I think they would want to pay the cost of attorneys and all the other cost of letigation,only to lose and owe for attorneys fees for both litigants in every case.
It would be extremely stupid for them to spend thousands of dollars to sue someone for a few hundred dollars.
They just hope that you are stupid and they can scare you into paying.