In the end, it comes down to how much of a hard time the officer wants to give you.
I once had three grenade launchers seized. The customs officer originally sent me a notice with 90 days to choose to abandon the shipment, appeal the decision or have it sent back to the country of origin.
So I contacted her to have the shipment sent back to the sender.
She responded with: "Sorry, the terms have changed. The item is now completely seized with no option for return. You may only choose to appeal it."
So I responded with a request for appeal and used my reasoning that all taxes for the item were paid on it, it was listed on the invoice/packing list, REAL M203 grenade launchers aren't even prohibited devices and are not even considered firearms.
She responded with: "It was not correctly declared on the packing list (she meant the long string of numbers and exact CCRA designation) and claimed outright that it was not listed on the invoice."
I responded with: "Yes it was listed on the invoice. The name you returned it to me as is the exact name on the packing list. I was even charged taxes on it."
She responded with: "Decision for appeal must be made within 30 days. Item is seized with no other option."
This completely contradicted the original notices sent to me. By that time, I was about 80 days in to the process because of all the back and forth. She just wanted to give me a REALLY hard time, and she was successful in doing so.