who can I repot harassing calls to?

Calling you at work it not illegal or harassment. Call them back and tell them you are not permitted calls at work. Get their address and then mail them a formal cease and desist if the debt is not yours.

I believe that you should call Absolute immediately and tell them explicitly that they are not to call you at your place of work. If they choose to persist, it would be in violation of the FDCPA. Other than that, you need to figure out if the debt is really yours. Call the collectors and ask them for details, send out a debt validation request via certified mail and check your own records in the meantime to verify the authenticity of the claim by going over your own documents like old bank statements and copies of your credit report.

First, there could most definitely be a violation of the FDCPA here. No, on the face, it is not illegal for them to call you at work. No, two phone calls do not constitute harassment. However, this is the key--what exactly was said in the voicemail they left? If they identified anything about the reason for the call, then they would be guilty of third party disclosure--the average person does not have two separate office numbers at their work that are "theirs", so this debt collector would have no good reason to call two numbers like that--and considering the fact that they called the boss, it was most likely intentionally done.

What did they say on the message they left for your boss? If they identified themselves as a collection agency, if they identified anything about the reason for the call, if they said you owe them money, etc etc etc, then they have broken the law.