Some companies take part in a program whereby they automatically receive updated credit card numbers. I know Amazon and Google both partake in this program; it's feasible Facebook does too.
Also it's possible the credit card that the OP is using is a corporate one used for other services too, and he/she is trying to solve this without having to change the payment methods for all the other services.
Charges could be disputed, though that takes a while...
I wonder how the account got locked in the first place, this is unfortunate.