Your original creditor has every right to transfer your account to a collection agency to attempt to collect on the debt if the account goes into default. In addition, the creditor is within its rights to transfer you to the collection agency when you call the original creditor to discuss the account. In fact, when accounts are assigned to collection agencies, it is standard practice for the creditor to insist that you speak with the collection agency to work out a repayment arrangement or settlement.
As for the collection agency representing itself to be Capital One, this may or may not be proper, depending on the collection agency's relationship with Capital One. Many creditors own their own collections divisions, in which case the collector can collect in the name of the original creditor. However, third party collection firms are generally required to disclose their name and the fact that they are not directly affiliated with the creditor, if the consumer asks for this information. Many third party collectors will state "I am calling on behalf of Capital One." Such a statement, while potentially misleading, is allowed, as the collector is not claiming to be calling from Capital One, only on Capital One's behalf. I am not sure exactly what the collection agency told you when they called, but if they claimed to be calling from Capital One directly, they may be in violation of the federal Fair Debt Collections Practices Act. I encourage you to read more about this law by visiting the Federal Trade Commission website at Ftc.gov.
If you are struggling to repay your debts, I encourage you to explore the options available to you to help repay them, such as credit counseling, and debt negotiation. To learn more about these services and which may be able to assist you with your debt, I invite you to visit the Bills.com Debt Help page.
I wish you the best of luck in resolving your debt problems, and hope that the information I have provided helps you Find. Learn. Save.