Packages are sometimes late. This reading walks through the response.
Check the vendor's advertised window
Every listing has a shipping window (e.g. 3-5 business days domestic Canada). Compare against how long it has actually been. If you are still inside the window, wait.
If you are past the window
Message the vendor politely. "Hi, my order [order-id] is now [n] days past the advertised window. Any update?" Wait 48 hours for a response.
If the vendor responds
Read what they say. Real delays happen (postal delay, supply issue, vendor's own scheduling). If the response is factual and reasonable, wait another 48 hours after the vendor's estimate. If not, escalate.
If the vendor does not respond
Message once more. Wait 48 more hours. If still no response, open a dispute.
Opening the dispute
Provide a factual description. Attach the message thread (which shows your polite unanswered messages). The moderator will contact the vendor. If the vendor does not respond within the moderator's window either, the dispute typically resolves in your favour.
What not to do
Do not spam the vendor. One message every 48 hours is fine. Ten messages in a day makes you look unstable and hurts your case if it goes to dispute.
Do not threaten the vendor. Threats end up in the message thread the moderator reads.
Do not finalise the order in the hope that the vendor will "reward" you by shipping. This is exactly the FE trap. Do not fall for it.