I cancelled my XXXX phone service XX/XX/XXXX. XXXX had provided me signal booster as I was not getting enough signal at my home. When I cancelled my XXXX service I requested for them to send me Signal booster return kit in order for me to return the signal booster to XXXX. The return kit simply contains the XXXX return label. But even after 1 month I never received the return Kit. So, I called XXXX again and again for the issue. Every time their response was that they forgot to send the return kit and will send me as soon as possible. At that time, I informed them that the delay is from their end, so I will not be responsible for any charges. Even after this conversation I did not receive any return kit. I had to call them so many times in order to send me return kit. Finally I received the return kit XX/XX/XXXX, more than 2 months after cancelling the service. Surprisingly, during these 2 months they started sending me letters saying I owe them more than {$400.00} as I never returned the signal booster. It seemed like there was definite disconnect between communication within their departments. 
As soon as I received the return kit, I shipped the signal booster on XXXX XXXX XXXX. I have a delivery proof showing they received it on XXXX XXXX XXXX. I have the XXXX tracking number with all the proofs including photocopy of return label, return kit, XXXX receipts with weight of the package showing XXXX, But to my surprise XXXX kept sending me bills showing I owe them more than {$400.00}. So, I called then again on XXXX XXXX XXXX to let them know the entire story and informed them the XXXX tracking number as well so that they can resolve this very simple issue. At this point I was thinking that I provided all the proofs of return and the issue will be resolved. But the biggest surprise was yet to come. I received a call sometime around XXXX XXXX or XXXX XXXX from Amsher Collection agency that XXXX has put my account in collection from XXXX XXXX which was just 1 day after I talked with XXXX representative and had given XXXX XXXX number as a proof of delivery. This seemed so brutal to me. But, I provided all the proofs to collection agency and disputed the issue on XXXX XXXX XXXX. Currently, this issue is in dispute since that day. 
I have all the photocopies as a proof to prove that XXXX definitely received the signal booster on XXXX XXXX XXXX and so I do not owe XXXX any money. At this point I feel like hitting a dead end. I really appreciate if you can help me resolve this issue.