the terms & conditions you agreed to in step 5 says:
Correction of Errors
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While our goal is a 100% error-free Site, we do not guarantee that any Materials or other content is accurate or complete, including price information and product specifications. If we discover price errors, they will be corrected on our systems, and the corrected price will apply to your order. We reserve the right to revoke any stated offer, to update content and Materials on our Site and to correct any errors, inaccuracies or omissions at any time without notice. We also reserve the right to refuse or cancel any order containing any error or inaccuracy, including after the order has been submitted, whether or not the order has been confirmed and your credit card charged. If your order is canceled after your payment has been processed, we will issue a full refund to the original pay type.