Changes to print data are generally not possible manually through Printlabs Support, as production is automated and print data cannot be edited manually.
Design changes are only possible while the status is Accepted — directly in your Shopify app, within 12 hours (or 30 minutes for priority orders).
Changes are also not possible in the case of a reproduction (e.g. following a complaint) — a reproduction always prints the existing design again exactly as it is. Changes to sizes or colours are also excluded.