Hello RichardB53,
Thanks for reaching out in Apple Support Communities! We understand you need help redeeming an iTunes voucher. We're happy to point you in the right direction to get this resolved.
Check out the section of this article that states "Code must be redeemed in a different country or region":
If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card
This article also has the link to contact Apple Support if you need additional assistance.
Thanks for using the Apple Support Communities, and have a great day!