You'll need to ask ebay to change the tracking number on the return. To contact them go to My eBay and click on "Help & Contact", top left. Scroll down to "Contact Us" and click on that. Select a topic, the nearest or any topic. On the next page, on the lefthand side you should get a link for "Chat with us".
You may have to select different topics until you get the chat link. If you end up using the wrong subject they will still help you.
