The OC isn't updating the balance. I'd wait until it's paid to address this. You could dispute, but that would just update it to now, they probably wouldn't keep it up to date and you'd have the same problem when it's paid off.
Just a Question, if best buy charged off the 3900 shouldn't their balance read 0 as the original creditor with a charged off status and the CA should have an accurate original balance of 3900, 2000 after reflecting payments??
As for the OC reporting, it depends upon what they are reporting.
Charge-offs have two separate reporting codes, one for the original amount charged-off, which would not decrease, and the other for the current debt balance.
If the OC has sold the debt, there is no more debt balance to them, so current balance should read $0. However, your credit file still contains the amount originally charged off. How is the amount being reported?
Debt collector reporting reflects the amount the amount of debt they are authorized to attempt to collect. If the debt collector purchases the debt, that amount also becomes the amount of debt owed to them. The debt collector should be decreasing the debt balance as payments are made, but they often dont.
If you wish your CR to accurately reflect the current amount of the debt balance, then you can certainly dispute their failure to comply with FCRA 623(a)(2), which requires a furnisher, once having reported information, to "promptly" update that information so as to maintain its current accuracy.
If the OC charged off the account and assigned it to a CA, they can both show the current balance. They should also both update with new balances as it is paid down.
If the OC charged off and subsequently sold the account, then then OC has to show a 0 balance. The CA would show the current balance.