double collection

I have received a letter from two groups asking for payment for the same debt from Century link. I have called Century link and they say I shold pay the collection agency. I think I am being billed twice for his debt. The name of the collection agencys are Convergece and the other CBE group. have paid the bill to Convergence and now have recieved bill from CBE and I paid then a third of the bill and set up two more payments. I think this wrong. How do I repaire this?:p