You could ask Costco for a refund of your CD purchase. If they won't do it, you could use this online refund request form to get a refund under the TurboTax Satisfaction Guarantee for desktop software:
https://support.turbotax.intuit.com/forms/refund-request.jsp
Otherwise, if you want to see if TurboTax would provide you a service code to use Online TurboTax on the basis of your Costco purchase, you could ask them. I'm not sure what they will say. They may just use the refund route and let you purchase Online TurboTax.
The problem, however, is that it like "comparing apples and oranges." Online Deluxe is not the same product as the Deluxe CD. Online Deluxe does not include a state program, for instance, while Deluxe CD version may or may not include a state program, depending on "which" version of Deluxe you bought. Online Deluxe also has form limitations which may require an upgrade to a higher edition, while the Deluxe CD version can prepare all the usual Federal forms.
In Online TurboTax a state return is 44.99.
In any case, if you want to speak to Support, here's how:
You can use the form at the link below to schedule a call back, or it may provide a number. Hours are 5AM-9PM Pacific (8AM-12 Midnight Eastern) 7 days/week.
Where the form asks what product you are using, be sure in the dropdown menu to indicate "CD/download" and the proper operating system, then indicate which Edition.
https://support.turbotax.intuit.com/contact
