Product: Debt collection

I used to have XXXX as my service provider in XXXX, but I was unhappy with their service and the level of consumer dissatisfaction, so on XX/XX/XXXX I switched to XXXX. 
XXXX had a promotion that they would pay the outstanding balance owed on each device to another provider for switching over. XXXX needed proof of the amount owed for each line transferred so they could cover such costs. I had 3 lines and for months after the transfer I had contacted XXXX to ask for the final bill with exact amounts owed for each line. 
They always answered that it would be sent by mail, but all I ever received was a lumpsome bill showing the total amount owed. That was not enough for XXXX, understandably. 
I tried go into my account online, but had lost access to the account because I was no longer an active client. I tried going directly to the store and they always told me they could not print it there. the last time I contacted XXXX customer service was online, so I requested a copy of our chat transcript which shows that I have been trying to retrieve my personal information before without any success. 
My struggle continued and to make this story short I went to the store for the last time and finally a manger was able to print the itemized bill. The same store that denied me to print the bill before and this time it was the store XXXX and I told him I was recording our conversation. That's the only reason he helped me. 
By the time I presented the bill to XXXX, the promotion had ended and they could no longer honor the offer since 3 months had passed since I switched over to them. 
Few months went by and XXXX presented me with a bill for {$2000.00} which was outrageous! It went from {$700.00} to over XXXX! My services with XXXX started on XX/XX/XXXX at exactly XXXX at the sore located at XXXX XXXX XXXX XXXX Unit B in XXXX CO XXXX. And yes I have records of it all. So I have been paying on the monthly cost of the cellphone devices for a little over a year and they still claim I owed over XXXX XXXX dollars! Absurd! 
So on XX/XX/XXXX I hired XXXX XXXX XXXX firm to resolve this issue with me. I have copies of all the mail sent by XXXX XXXX, XXXX. on my behalf. At that time XXXX had turn the case over to a collection agency named XXXX XXXX XXXX XXXX. 
XXXX never replied to my attorney and for months I never heard from XXXX either. I requested response on the case but never got anything. 
Just recently a new collection agency named XXXX Collections located at XXXX XXXX XXXX XXXX XXXX XXXX, IL XXXX started sending me settlement letters by mail. Their contact number is XXXX on behalf of XXXX account number XXXX for the settlement amount of {$1000.00}. I want to dispute that charge too. So XXXX did not respond to my attorney in nearly a year and now they just hire yet another collection agency to start this charge all over again? How about replying to my previous attorneys request?? 
I not only want to dispute this charge, but I want to charge XXXX for damaging my credit, for defamation and for the fact that I pay higher interests due to this allegations on my credit report! Not even accounting for the harrassing calls! 
It's about time someone fights back against all the injustice caused by reckless cell phone companies! 
Sincerely, XXXX XXXX