HSN QVC Never credited my bill Florida

I was making payments on my bill but I noticed that the bill was not decreasing. I call Sychrony Bank to get a final bill and they switched me over to hsn.

hsn told me my final payment and I paid the bill. About a week later I get a email saying I am late on my payment . I  called Synchrony bank and all I got was a big run around how they are a third party  company, they called hsn confirmed my payment but still said I owed them the original balance. I have confirmation number and dates.