Disputing Debt Collection Letter

I'm writing a letter to debt collection to dispute a debt. Here's the letter so far:

**** Johnson, a.k.a **** Benson * Flagg Hill Rd Heath, MA, * mail@satch.xyz (*) *-* August 20th, * Diversified Adjustment Service, Inc. * Coon Rapids Blvd Coon Rapids, MN * Re: Dispute of Alleged Debt - Verizon Wireless Account Number: * To Whom It May Concern, I am writing in response to your letter dated August 19th * regarding the alleged debt associated with the account number * (reference number *). I wish to formally dispute the validity of this debt. Please consider this letter as a notice that I do not owe the amount being claimed for the following reasons: *. The only given explanation of this charge was in an email I received on July *, *, saying ‘Your bill is now available on My Verizon. We see that all lines on your account are disconnected, so outstanding balances and future bills will be mailed to your billing address.’. When prior to this I canceled my postpaid phone plan with Verizon I did not disconnect my line, but simply switched to prepaid. I am still a customer of Verizon and have paid monthly bills to Verizon without interruption for my phone service. If any extra charge was to be associated with the switch to prepaid, I should have been informed. As I was not, Verizon should not have billed me any more than the standard cost associated with my phone service, which they did and I have paid. *. When Verizon debited $*.* from my checking account ending in * on July 31st, *, as this transaction was without my specific consent and knowledge, I called Verizon immediately to complain. They could not find any record of this charge, saying on the phone that they could not access details of my postpaid account once I had become a prepaid customer. They told me over the phone that they would look into the issue and get back to me within 14 days. I did not receive any communication from them until August 19th, when I received an email saying that I had a balance on my account of $*.*. This email did not make reference to or address the conversation we had on the phone. I called my bank and told them that this transaction was unauthorized, and they as a courtesy provided me with a temporary refund of $*.* which they never took back. If Verizon gave the money they took from me back to my back, I was not notified of that. Therefore, since Verizon did not explain to me the cause of this charge at all, let alone within 14 days of my phone call as they promised, they cannot expect that I pay the money. **** Johnson, a.k.a **** Benson * Flagg Hill Rd Heath, MA, * mail@satch.xyz (*) *-* August 20th, * Diversified Adjustment Service, Inc. * Coon Rapids Blvd Coon Rapids, MN * Re: Dispute of Alleged Debt - Verizon Wireless Account Number: * To Whom It May Concern, I am writing in response to your letter dated August 19th * regarding the alleged debt associated with the account number * (reference number *). I wish to formally dispute the validity of this debt. Please consider this letter as a notice that I do not owe the amount being claimed for the following reasons: *. The only given explanation of this charge was in an email I received on July *, *, saying ‘Your bill is now available on My Verizon. We see that all lines on your account are disconnected, so outstanding balances and future bills will be mailed to your billing address.’. When prior to this I canceled my postpaid phone plan with Verizon I did not disconnect my line, but simply switched to prepaid. I am still a customer of Verizon and have paid monthly bills to Verizon without interruption for my phone service. If any extra charge was to be associated with the switch to prepaid, I should have been informed. As I was not, Verizon should not have billed me any more than the standard cost associated with my phone service, which they did and I have paid. *. When Verizon debited $*.* from my checking account ending in * on July 31st, *, as this transaction was without my specific consent and knowledge, I called Verizon immediately to complain. They could not find any record of this charge, saying on the phone that they could not access details of my postpaid account once I had become a prepaid customer. They told me over the phone that they would look into the issue and get back to me within 14 days. I did not receive any communication from them until August 19th, when I received an email saying that I had a balance on my account of $*.*. This email did not make reference to or address the conversation we had on the phone. I called my bank and told them that this transaction was unauthorized, and they as a courtesy provided me with a temporary refund of $*.* which they never took back. If Verizon gave the money they took from me back to my back, I was not notified of that. Therefore, since Verizon did not explain to me the cause of this charge at all, let alone within 14 days of my phone call as they promised, they cannot expect that I pay the money.

give me the language to request validation