The delivery date that you received is just an estimate, it can take less time or more. Since your purchases were on a Friday they may not have been mailed until Monday, Sept 16th so it has been less than 2 weeks. It often takes longer for international mail.
Do you know how to check to see if the items have been shipped and/or if you can get any information from a tracking number? If not,,,Click on My Ebay on the top of the page, then click on purchase history on the left side of the My ebay page. To the right of each item there is a $ sign that should be highlighted since you did pay. The next icon is the shipping icon. If you hover over that, it should tell you if the item has been shipped and when.
Underneath each item on that page there may be a tracking number. You can click on that for information about the package but the tracking on first class and Priority small flat rate box is not always complete. You can also go to canadapost.ca and enter the tracking number there.
To contact the seller- To the right of the item you should see 'more actions' with an arrow next to it. Click the arrow and it should say something about contacting the seller. When you click on that, if it gives you an option for topics to choose from, use 'Other".