Final answer:
The customer's main issue is a payment issue due to their card being declined while trying to purchase gifts for the holiday season.
Step-by-step explanation:
The customer's main issue, as described in the given scenario, is a payment issue. When a customer's card gets declined, it suggests that there is a problem with the payment method being used, which can be due to a variety of reasons such as insufficient funds, a hold on the card, an incorrect entry of payment details, or the card being expired.
Regardless of the payment method issue, the customer is unable to complete their purchase, which is particularly frustrating during the holiday season, a time typically associated with buying gifts.