Return monthly billing?

I sent a laptop back to Amazon, part of the laptop was used to pay the new bill, but half the money is gone? Will this be transferred to my bank account now?

If you have stated on the return that it should be transferred to a bank account, it will be transferred. Otherwise it will be credited to you as Amazon credit.

In the case of returns, the money is usually always credited to the same payment method as was paid for. When transferring to a bank account, for vouchers to the Amazon account