Product: Debt collection

AFNI send me a letter about a debt that I supposed had with XXXX on XX/XX/XXXX. I decided to call and ask for the legitimacy of that debt and I ask for the original contract of that account and see if the debt that I supposed owe is legit. AFNI in that conversation told me that they can proof the debt and supposed to send via email the contract but they fail and they send me a letter like offering a discount the first amount was {$900.00}. The discount offer when I ask for the contract they dont gave me proof of the contract but decide to make an offer I dont know why. Because the first communication I was clear about my rights under the FDCPA and I ask to the collector the original contract for see the legitimacy of the debt but THEY FAIL. When I received the discount offer of {$450.00} without a reason about that because I ask in that call to the AFNI collector the original contract for the legitimacy of the debt because I want to see my supposed sign in that contract. They fail the first time and send a offer, I decided call again to AFNI and the person that I talk was very unprofessional and was rude. I ask multiple times on the call for the original contract to see the legitimacy of the debt. The AFNI collector when I ask again for the contract of that supposed debt, she gets angry and start argue things like, that I need to pay the debt trying to intimidating me that I dont had rights about ask for the contract the only thing she can do is ask SPRINT but at the moment AFNI cant send me the original contract and they decided by today send me another letter with a bill but I dont ask for any bill. This people are using tactics very unprofessional to make me pay something that they cant verify thats a crime I think I was clear and I ask for the original contract and they fail two times and still sending letter. This year I want to buy my home and AFNI can affect my credit and I want to make a claim because if they could proof that the debt its not mine they need to stop reach me because they fail two times to show me the legitimacy of the debt. I had all the letter from AFNI and the discount offer that I never ask for I ask for the original contract and all the calls with AFNI are recorded. The first person that I reach was very professional but they fail on send me that first time the original contract and send a offer. The discount offer that AFNI send was of {$450.00}. This people are very unprofessional and they want that I pay something that they dont can proof its mine. I was very very clear in my verification debt and that was the original contract. AFNI had all that conversations in record I was very clear and I ask multiple times for the original contract but the female that I talk that day was very disrespectful. At the end of the call she was very unprofessional she start say hello a lot of time to make me angry and hang the phone. I want to resolve this thing I never had problems with my credit and this situation can affect my credit score and this year I want to buy a home I dont had any collection of any type. If AFNI cant proof thats my debt they need to leave me alone because they still sending letters without proof that its my debt. I know all the conversations are recorded and I was clear in my order. The days that I make communication with AFNI was on XX/XX/XXXX and the second call was XX/XX/XXXX. They had all the conversations recorded of those phone calls that I make and I was clear of my order in those 2 conversations, I ask for the ORIGINAL CONTRACT, not a bill. Sorry for my bad English my first language is XXXX.