As it states in your order confirmation email, “If your order contains multiple products, products may be shipped separately.” As separate shipments often come from different printing facilities in different parts of the US, it is not uncommon for parts of your order to arrive several days apart.
If the final part of your order has not arrived within 3 weeks of your order date, please let us know and we will ask our photo fulfillment partner to send you a replacement order.
That said, you may wish to check with the other members of your household before contacting Bunk1 to see if any of them may have received the remaining item(s) and neglected to inform you.