From a business perspective, there should be several options that would be workable for Nikon Melville:
1. You could wire transfer funds from your bank to their bank. Ask to speak with Nikon's accounts receivable administrator to get details on the account to wire to and a number to load into the reference box on the transfer form.
2. You could mail a check or money order to Nikon Melville. You noted that Nikon does not have an account with Western Union, but that is a bit different. Buy a money order (or get a certified check) at your bank; then mail it to Nikon.
3. You could use a debit card and Nikon could verify the funds immediately.
International experience must be common at Nikon and I believe if you talk with the right person you can get this resolved. The right place to contact is Nikon.

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