AT&T Lost my returned equipment - DirecTV

In May 2014, I discontinued my service for ATT U-Verse. I was sent the boxes to return my equipment. On May 4th, 2014 I took the boxed equipment to the local UPS store for return. They processed the return and gave me the CPE Return Receipt and the Tracking Number. The equipment reached its destination on 06/05/2014 in Yuma, AZ at 9:02am and was signed for by someone named Thomas.
Several months later, I discover a collection on my credit report for the U-Verse Equipment I already returned. I called AT&T several times and tried to get this resolved.
Fast forward almost two years to October 2016. I called AT&T and spoke with a agent named Maria, who assured me they would get to the bottom of this matter, escalated the issue and said I would receive a call in 24-72 hours. That call never came. Nor any other form of communication.
On 11/09/2016 I called again and spoke to Jacob. Same story, issue elevated, wait for phone call in 24-72 hours. Once again, no call.
Today, November 14th, 2016, I connected via chat to Christian D. whome did the exact same thing except this time tried to pin me on a random late payment. I told him I would rather pay the full amount of the "missing equipment" to hire an attorney to fight this case and for damages that has been done to my credit report. I was once again told to wait for the phone call.
So on Thursday, Nov 17th, after 12:15pm, I am calling back. If I don't get some answers, I am hiring an attorney. I will also report AT&T to every available agency I find to report them too and also be sure and give them a 1-star rating everywhere online.
For all the trouble this has been and for them refusing to actually step-up and resolve this, it is time for some retribution to them.

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