Changes to the raw material or variant (e.g. a different size, colour, or shape) are generally not possible manually through Printlabs Support, as production is automated.
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 for a reprint (e.g. following a complaint) — a reprint always uses the ordered variant.