Convergent sounds fishy to me, Internet

Just got a letter in the mail from Convergent saying I owe $104.73 for Verizon California. I lived in California 10 years ago but never had an outstanding bill them. First it seemed fishy that the letter was sent from Michigan, the address on the letter head has an address from Texas and says to send the payment to Renton, WA. I paid all my debt off 2 years ago. I looked at my credit report from 2 years ago and one from now and there is no report about this bill at all on them. My husband tried to call and have them send a copy of the bill , they hung up on him twice and the third time he sat on hold for over an hour and we can still not get a hold of them. This better not wreck my credit.