My question involves collection proceedings in the State of New Jersey

If OC states on all 3 credit reports that my defaulted "private loan" was sold and paid by a guarantee agency and it shows a zero balance and states "PAID OFF" but yet I am being sued by a third party collection agency in the OC name as plaintiff, how can that be? Also, the servicing agency who serviced my loan says the loan was transferred to collection agency. How can I find out who truly owns the loan? OC & servicing agency both tell me to call collection agency. Could perhaps the collection agency is the true owner now and maybe also JDB who bought the loan for pennies on the dollar and is suing me under OC's name, which, wouldn't that be fraud?