Written notification about debt: Debt collection

I am filing a complaint against First National Collection Bureau , Inc. regarding an alleged debt of $7800.00, which I dispute and do not recognize. At least one collection letter was sent to a workplace address where I am no longer employed. I did not provide or authorize this workplace as a valid contact address. A staff member at that workplace opened the letter, and it was clear that it was a debt collection notice. This exposed my private financial information to a third party. I have been informed that additional letters may have been sent to that location, but I have only personally confirmed receipt of one. I did not consent to being contacted at any workplace. I consider this to be improper third-party disclosure and inappropriate communication practices. I dispute the validity of this debt and request full validation, including documentation that the debt belongs to me and that the company has the legal right to collect it. I also request that all communication be conducted in writing only and that no contact be made to any workplace. I am requesting investigation into this matter and appropriate corrective action.