Product: Debt collection

I had received a notice in the mail from Frontline Asset Strategies ( dated XX/XX/2019 ) on or about XX/XX/2019 indicating that an account allegedly owned by me had been placed with them for collection. The current creditor name listed on the notice from Frontline was XXXX XXXX XXXX and the original creditor name was listed as XXXX XXXX XXXX  XXXX. The alleged amount owed was {$630.00}. I do not have any account, contract, or business relationship with Frontline Asset Strategies, XXXX XXXX or XXXX XXXX XXXX. I disputed this debt within 30 days of receipt of their letter and on XX/XX/2019 I had sent Frontline Asset Strategies a written notice requesting validation of this debt and had sent it via USPS Certified Mail with signed delivery confirmation requested. I had indicated that this is NOT a request for verification or proof of my mailing address, but a request for VALIDATION made pursuant to 15 USC 1692g Sec. 809 ( b ) of the FDCPA. I requested that their offices provide me with competent evidence that I have any legal obligation to pay them. I had specifically requested that they provide me with a copy of the agreement that bears the signature of the alleged debtor wherein he/she agreed to pay the creditor as well as a copy of the agreement with their client that grants them the authority to collect on the alleged debt. I had received signed delivery confirmation from the U.S.  Postal Service indicating that my correspondence to Frontline Asset Strategies was received and signed for on XX/XX/2019. 
Frontline Asset Strategies had then responded via a letter dated XX/XX/2019 and indicated that the attachments and information provided with this letter is information that your current creditor is able to provide to us for you at this time. Frontline had attached copies of billing statements for a XXXX XXXX account with their correspondence, however, they had failed to provide the requested verification of any signed contract or agreement that bears a signature. In essence, they essentially admit that they are unable to provide proof of a signed contract at this time since the only information provided by them was copies of billing statements. Copies of billing statements are not sufficient proof of a legally binding signed agreement or contract. 
On XX/XX/2019, I had also received a letter from XXXX XXXX XXXX indicating that they manage the account for XXXX XXXX XXXX and that they had initiated a review of the inquiry they had received. 
On XX/XX/2019, I had received another letter from XXXX XXXX XXXX indicating that they received a recent inquiry regarding the account and have enclosed an account summary which provides verification of debt. They had failed to provide verification of a contract or agreement that bears a signature. 
Since Frontline Asset Strategies and all of the affiliated entities involved with my request for verification of this debt ( XXXX XXXX and XXXX XXXX XXXX ) have all failed to provide competent evidence and proof of a signed contract or agreement, I hereby am requesting that all collection activity by Frontline Asset Strategies, XXXX XXXX and XXXX XXXX XXXX immediately cease and desist. I am also demanding that this account which is currently showing on all three of my credit reports from XXXX, XXXX  and XXXX as a negative collection item under the name of XXXX XXXX XXXX be immediately and indefinitely removed from all of the credit reporting bureaus since Frontline Asset Strategies, XXXX XXXX and XXXX XXXX XXXX are all unable to provide competent proof of a signed contract which proves legal ownership of the stated account.