UCB - United Collections Bureau untied collection beauru They are commiting identiy fraud toledo, Ohio

I had a old Verizon bill had payment arrangements set up with them,they then sent it to UCB Collections where instead of contacting me with the account they contacted my ex-inlaws saying that I commited Identiy Theft to obtain my services and unless my ex-mother in-law reports it to the police it will go onto their credit report.I have all the orignal documents from Verizon( order confirmation,phones bills)all in my and my ex-husbands names but they still refuse to change the information.I donot know what to do I have rewuested all communication to be done in writing they call my ex-inlaws 20 times a day they will not even talk to me called my a criminal and on top of everything eles my old bill from Verizon was only $178.28 and UCB is trying to charge me almost $2000.00,Please someone help!