Disputing Debts: Lender Sold Student Loan to Collections Found Out Loan Not in Default

My question involves collection proceedings in the State of: NY I have spent all day calling every US education department even US education default resolution dept I signed into my government student loan website checked credit report checked county clerk NO DEFAULTS found. So I have Navient who sold my loan HESC who purchased my loan they are the only ones that can fix but refuse to each tell me other is responsible I have approx 50 days to clear up I need advice where to turn. Tomorrow I will try an obudsman fill out some papers on these companies to US fraud beau I'm at my end this is not right any advice would be appreciated I posted before and was spoken to nicely I'm

Just looking for advice like e wry one else thank u

Disputing Debts: Lender Sold Student Loan to Collections Found Out Loan Not in Default