If your shopper is saying that they were charged, but you don't see any record of their order in your e-commerce platform or within your Sezzle account (under the "Orders" page), they're likely seeing a pre-authorization charge, which is just a temporary hold on the funds.
Nearly every card processor will pre-authorize funds for a transaction, and when the transaction does not complete, those pre-authorizations do automatically fall off. Typically, this happens within the hour, but depending on the shopper's payment method, it may take up to 3 business days. These charges are typically found in the "pending" section of their payment method.
In situations like these, we recommend having the customer reach out to us directly, as we can provide them with more information specific to their order and their account. They can reach us at email@example.com.
If you do see that the order came through to your Sezzle account, but you can't find it in your e-commerce platform, please reach out to us at firstname.lastname@example.org so that we can investigate further.