Yes, upgrading the shipping method for an existing order is available for orders that have not been shipped.
Please email us the details via our Contact-Us page with the heading 'Modify order (pre-ship)'. We need the details for the shipping method you would like to change and your existing order number. If you don't know your order number, include the email address with which you used to place your original order.
If you give us the wrong information and our staff is unable to find the order, and/or the order has been shipped while waiting for your  reply, it will not be possible to modify the original order. So please double-check your information before sending it to us.
Our support staff will contact you during business hours and send an email regarding the changes to the order with the heading "payment needed to update order". You can confirm the changes in the email, and click the Pay now button to deposit the difference. After the payment has been received, the order will be shipped during normal business hours.
If it's urgent and you don't have the time to wait a response, we recommend you cancel the existing order and place a new one. This is the fastest way to get your package because you will not have to wait for a response.  In this case, please contact us via our Contact-Us page with the heading 'Cancellation (pre-ship)' to cancel your existing order.
Please note that cancellations are not available after the order has been shipped.