USPS said they delievered my package but it never reached my mail box?

So I ordered a brand new Iphone 5s off of ebay because my other one was unfortunately stolen. When I did get the phone I wanted to exchange it because it wasn't the color I had ordered so I sent it back. The seller emailed me the tracking number so I was able to track it, it said it was delivered on the 29th of june (which it wasn't, not even a notice note was left in my mailbox because that phone was over 250 bucks it should of been required a signature right?) but I never got it. I contacted USPS since the package was shipped back via that mailing service and they said they would call me back and check with the mail carriers to see if they saw my package anywhere or remember delivering it. Weeks have gone by and they never ******* called me back. They don't even have a real customer service line. In conclusion I have decided to never ever ship via USPS again. But my package is still missing and my seller is refusing to give me a refund because the tracking number says it was delivered. I also opened up a claim with USPS and of course they denied it because the tracking number said it was delivered when it obviously wasn't. I'm so ******* angry, not only did I not pay for this phone (My mom is not very wealthy and she worked her *** off to try and buy me this phone FOR THE SECOND TIME) but I'm struggling and losing hope for my phone. Is there anything I can do? Is there anything ebay can do with or for me?

Did you ever stop to think that the phone could have been stolen out of your mail box? Happens every day. Neither USPS nor the Seller will be willing to compensate you because of this. Since tracking shows as delivered eBay/PayPal will not be helpful either.

Not what you wanted to hear, I know. Sometimes bad things just happen.

Order from a more reputable source. And also request signature confirmation next time.