This can happen for many reasons, so no worries, we've got you covered!
With our 7-day return and refund policy, you can purchase and apply for instalments risk-free: if your instalment request is not successful, you can return the item for a full and immediate refund within 7 days.
You can also let us know using the chat function on our site and we will hold your order until you have the credit card issuer's confirmation. If unsuccessful, we simply cancel the order and refund you in full immediately.
Related question: Can I pay by instalments?