their system takes several days to reflect payments - even if you're on time. The morning after your payment is due they start making calls and those calls will continue until their system reflects the payment - which may take several days.
This message was from Sychrony Bank (Amazon), in regards to my account. Although not a debt collector in the stalking type, they did call about a payment.
Readers:
Be Safe, Not Sorry
Rather than believe the posts in this thread, or the words of an anonymous caller,
if you are notified of a problem with your card,
CALL THE NUMBER ON THE BACK OF YOUR CARD
Even though the number in this thread might belong to your card issuer, the scammers can easily spoof what appears on your CallerID, and attempt to get your precious ID and card data!