Yes. If one wants all debt collection contact to stop, and it is a debt collection agency rather than the original creditor who is contacting/calling, one has the right to request that they not contact the debtor again. This request must be in writing. Make sure to include a statement that the letter is not meant in any way to acknowledge that one owes this or any other sum of money. Mail the letter certified, requesting a return receipt so that one has proof of its delivery. Once the agency receives the letter, its employees can only reach out one more time to explain what action they plan to take. After that, contact must stop.
One can also request that a collection agency not call at one's place of work. Send the same type of letter discussed above and instruct the debt collector to refrain from contacting one at work. By law, the debt collector must comply. Remember, though, stopping the contact does not stop the debt-collection activities. The debt collector can still send negative information to the credit-reporting agencies, sue one in court, and garnish one's wages or file a lien against one's property once a judgment is issued by the court.