Lost in the mail

I Mailed my phone's back to eat to you and AT&T, as instructed. Somehow they never received the phones. So now they are charging me for the 4 phone's. I've been talking with customer service and their supervisor's for the past 5 months. They've told me that they are escalating the issue for investigation. I just spoke with someone else and they told me that they didn't see any investigations that were done. Several people told me that I would receive a phone call from them (the supervisor, receiving or the investigation team), from 1 day to a week. I would never get a call back. I just started with AT&T, as of right now I'm Very disappointed with them. Sents I've been dealing with this issue i have found that this is a on going problem with them for several years now. One would think that if you had a constant problem one would change the way they did things. I can only speculate why they don't change.