Overview:

No refunds and no exchanges per SiGMA Terms. Student Passes are non-transferable. For name changes on paid passes, contact Support (not guaranteed).

Details:

Refunds: “All purchases are non-refundable.”
Exchanges: “We do not offer exchanges for events…”
Rescheduling: If an event is rescheduled, your tickets remain valid for the new date.
Student Pass transfers: Not transferable; valid for the registered attendee only.
Name change on paid passes: Not explicitly detailed on public pages. Action: contact SiGMA Support with order details to request a name change; approvals are case-by-case. (No guarantee stated publicly.)

Source: Terms & Conditions; Student Pass