If you are experiencing check out errors there could be a few reasons why:
First, make sure you wrote the right credit card number, and billing address for the credit card you are using. Did you write the correct postal code? That's the most common mistake.
We recommend checking your bank statement, maybe some annoying autopayment wiggled its way in and sucked your money before us (hehe).
If you're trying to pay with PayPal you could clear your browser, and delete old cookies. If nothing works, try back in a few hours.
If an error still persists maybe you should try with another card, or send us an email to email@example.com and we'll figure it out ASAP, or at least help you with your purchase.