What can I do to stop receiving upsetting telephone calls about debts I don't owe? The telephone caller knew my social security number and bank accoun

Sounds like identity fraud.  Tell the agency, they should send you papers affidavit, stating that not your debt.  Otherwise, hire an attoeny, to handle it.

Ask for the collector's name, company name, mailing address and phone number. If they are a legitimate debt collector, they should provide you with that. Then you can send them a letter, requesting that they stop contacting you about the debt. Under the Fair Debt Collection Practices Act (FDCPA), a "third party" debt collector is required to stop contacting you, once you request it in writing. They can contact you one more time, to tell you that they will be ceasing contact, and that what actions they intend to take next. Unfortunately, there are a number of shall we call them "cowboy" or "renegade" debt collectors nowadays, that operate outside the law, if not offshore or outside the United States. A number of my clients have been receiving them, often for many-years-old defaulted payday loans. If you have one of these renegade collectors calling you, and they won't stop, you may want to contact your telephone company for a feature called "privacy manager" that will not allow your phone to ring, unless the caller enters a code (that you have provided them ahead of time).