allied collections collections for sprint harrassing, rude and nasty Nationwide

i cancelled my account with sprint back in july 2016and paid off my account in full and returned my phone to the store like i was supposed to, the sales girl in the store on july 16th took the phone ( 2 )  of them and said that the changes would be noted to the account and that that was it no receipt was given she said that i did not need one , I knew that i should have insisted on getting one but i did not get one i just left the store, approx 3 months later i get a bill from sprint stating i owe $ 482.86 for equiptment not returned to them, i called them up and they were to start and investigation another 2 months go by and i hear nothing, and i call back and i am told that i wasnted to know the status of the claim that i put in and there response was that it was still being investigated, but it looks like charges are being reversed and i should reseve an email ina few days,

well about 4 weeks go by and i receive another amail requesting the money for the equiptment so i call back again and inquired status and they informed me that there was no invesigation being done, so i demanded one be done that this was insane, so they started one and gave me a case number and after another few months of not hearing nothing i called back, and that is when i was told that my account was now turned over to collections, and then my call was terminated... and then at 930 pm i received a call from allied collection 866-377-3956 ( claming to be allied collection agency ) , wanting personel information to settle this matter from me I REFUSED TO GIVE THEM ANYTHING AT THIS POINT AND I TOLD THEM THAT I WANTED SOMTHING IN WRITTING FROM THEM TELLING ME WHO THEY WERE AND THEY SAID OKAY, AND STILL WAITHING FOR THEM TO SEND ME SOMETHING TO THAT EFFECT. if they are a legit company then they can send me paperwork, insead of harrassing phone calls all day