The federal Fair Debt Collection Practices Act (FDCPA) gives you specific rights when you are contacted by a debt collector. They include the right to tell a collector not to contact you at work if your employer does not want collectors calling you there. If you tell a collector not to call you at work anymore, follow up the conversation by sending the collector a letter instructing him to cease calling you at your place of employment.
If a collector continues calling you at work after you've told him not to, the collector is breaking the law and you should get in touch right away with a consumer law attorney in your area who handles debt collection cases. Find out how to get FREE or low cost legal advice about debt collection from a consumer law attorney here. You may have grounds for legal action against the collector.
Send your letter certified mail with a return receipt requested. The receipt provides proof that your letter was received. Also, make a copy of your letter before you mail it and file the copy for safekeeping in case you need it later.
The FDCPA also gives you the right not to be harassed by debt collectors. Harassment includes being called repeatedly during the same day about money that you owe. Given the frequency of the collector's calls to you, he is probably breaking the law. Again, this is something you should discuss with a consumer law attorney.
It's important to begin keeping a written record of your interactions with the debt collector. This information will be helpful if you decide to work with an attorney. An easy way to do that is to use my Free Debt Collection Worksheet. Keep a copy by your phone at home and at work so you can record when the collector calls you, what the collector says, and so on.
Good luck resolving your debt collection problems!