There are 2 scenarios:
A) The purchase value of all the items you’re keeping is less than the value of the redeemed gift card.
In this case, the gift card will be used to pay for the items that you keep. The rest of the original gift card amount will be restored. Any additional amount paid will be refunded to the payment method that you chose.
Example: You buy clothes worth 100€. You pay 50€ with a gift card and 50€ with a credit card. You only keep clothes worth 40€. 10€ will be paid back to your gift card and 50€ to your credit card.
B) The purchase value of all the items you’re keeping is higher than the value of the redeemed gift card.
In this case, the gift card will be used to max. The rest will be paid using the payment method you chose and the refund for additional amount will be returned to the same payment option.
Example: You buy clothes worth 100€. You pay 50€ with a gift card and 50€ with a credit card. You keep clothes worth 60€. Your gift card will be maxed out and 40€ will be paid back to your credit card.