A collector does have the right to contact you concerning a debt they believe you owe. However, the debt collector must first validate the debt with you before continuing correspondence with you. The collector needs to send a letter to you to validate the debt. You have 30 days to respond to acknowledge the debt or dispute it in writing.
The collector can still obtain proof of debt from the creditor the debt was incurred with. After this time, the collector may begin correspondence again with you. Fortunately, you can request for the collector to stop contacting you. Such a request should be sent in writing via certified mail with a signed return receipt showing the letter was delivered to the collector. The FTC recommends making a copy of the letter before you send it for your records. Upon receipt of your letter, a collector can only legally contact you for two reasons, first to advise they will no longer contact you and last to advise of any specific action they may take, such as a lawsuit.
According the the Fair Debt Collection Act (FDCPA), collectors can not contact you at will. This means collectors can not contact you, without consent, before 8am or after 9pm on any given day. In addition to these time constraints, collectors can not contact you at your job after they have been notified your employer does not allow such calls.