Complaint Review: Yellow Pages Online Services

I have just started my business and I signed online for the Real YP (free service). Few days letter I received a letter from this Yellow Pages Online Services (which is NOT the real YP ) asking to confirm my data.

I did not understand it was a fake service and I proceeded.

I sent my Company information in and few days later I received a $329 Bill. 

I called the toll free number indicated in the bill and I asked to cancel everything because I never asked to have the service.  He answered me that he can cancel my service (for the future..) but I have to pay for the current bill.

I told him I did not sign accepting a charge whatsoever but he reply that in the back of the letter with small words everything was clear and I have to pay.

He then threaten me to pass the bill to a Collection Agency.

Anyone had a similar experience? Solutions ?