How to account bank charges for refund received from supplier?

Hi Gurus,

We received a refund from customer through wire say 1550 and my debit note is of 1600, though customer wired 1600 we received 1550, as intermediate bank deducted bank charges of $50.

Now my accounts team need to close this debit note or a invoice.How do i account Bank charges of $50 against an invoice / debit note during refund.

The bank charges vary each time.

Please help me out

Thanks in Advance

Praveen