This fix adds a new text so at checkout_payment.php when a GV is redeemed/applied to an order with the redeem box, it says "The gift voucher has been successfully added to your gift certificate account for "... instead of "The coupon has been successfully applied for "... It also clarifies a little bit what to do after a voucher has been applied to their account. See enclosed Screenshot.

in catalog/includes languages/YOUR LANGUAGE(s) HERE/add ccgvdc_english.php:**REPEAT WITH ALL LANGUAGES YOU USE***

FIND:
define('ERROR_REDEEMED_AMOUNT', 'The coupon has been successfully applied for ');

ADD AFTER:
define('ERROR_REDEEMED_AMOUNT_GV', 'The gift voucher has been successfully added to your gift certificate account for ');
define('ERROR_REDEEMED_AMOUNT_GV_2', 'You may now use this as payment below by checking the 'used from Gift Vouchers box'.');


in catalog/includes/modules/order_total/ot_gv.php
FIND:
tep_redirect(tep_href_link(FILENAME_CHECKOUT_PAYME NT, 'payment_error='.$this->code.'&error=' . urlencode(ERROR_REDEEMED_AMOUNT. $currencies->format($gv_amount)), 'SSL'));


CHANGE TO:
tep_redirect(tep_href_link(FILENAME_CHECKOUT_PAYME NT, 'payment_error='.$this->code.'&error=' . urlencode(ERROR_REDEEMED_AMOUNT_GV. $currencies->format($gv_amount).'. '.ERROR_REDEEMED_AMOUNT_GV_2), 'SSL'));


More...