Entitled to a rebate for unauthorized texts regarding advertising

I upgraded my iphone on feb. 28, 2015. Was given an self addressed Verizon envelope, USPS, to mail in my old iphone. I did so, on March 4, but after 2 weeks, received text that they did not receive the phone. I had the tracking # but it showed nothing even though I did mail it. Called customer service, and the rep said they did have my phone under another tracking #. I did not write down the new tracking number she had given me.Thought all was fine, but 3 weeks later received text from Verizon saying they still did not receive my phone. Called again, they said they did not receive the phone. Nothing in the notes of the previous phone call. Customer service rep says I should not have used Costco. They claim to do an inventory search but still could not find my phone. Fast forward to May 10, I am charged $299 for not returning the phone. Verizon customer service says to file a claim with USPS. This is outrageous and unfair. I suspect others have had this problem with Verizon/Costco.

Hi! I on November/ 6 /2013, I purchase 2 new L G- UN150S cell phone at Costco, through the phone service providers, the sale person set me up with Verizon provider, I was told to mail in my rebate information, which I did the next day on November 7 2013, & Verizon would sent me $70.00 rebate credit for my new phone, to this day I have not receive anything.
I'm the only person each day checking all the mail as soon as it arrive into my mail box, so we can't blame my husband!
I call Verizon, they mentioned that there was nothing they could do! to contact online "Costco-Stuart Lee rebates" which I did, but couldn't get anywhere. if you believe you can help me with this issue, please contact me at: [email protected] .
Sincerely.
Francoise Paul & Alan McKenry