US-Yellow Pages review: Scam 1

A couple weeks into my new position as director at a child care center I received a "Listing Order
Form" to review my company information. I updated my information, signed
the form thinking this was the customary FREE service they received
previously. Today I received a bill from
US-Yellow National Yellow Pages for $1145.00 with a xerox copy of the
form I updated and signed for a free listing. After doing some internet
searches, I discovered there were many complaints of this scam from
others in regards to this company in Jacksonville Florida. Since I
was tricked into thinking this was for the legitimate yellow pages and I
signed a document for what I thought was the FREE listing, am I
obligated to pay this invoice? From the other complaints I have read
about this company, many have refused to pay and received threatening
phone calls from this company as well as collection agencies. Can this
company put a negative mark on my credit? I would have called to canceled if i would have recieved any other bills before now. After I called to try to cancel they said it had been too long.