Collections harrassament

I added my son to my credit card account. they sent him a credit card wihh a different account number and he ran up a large debt. Who is responsible, him or me? Can a collection agency harrass me at work about this debt?

Yes, unfortunately. It is your account, they simply added his name to yours. He most likely doesnt have any credit, and would be under yours.
You could probably call your credit card company and change your contact information, this way they will not have your work number.

Depens on his age, of course. If he's over 18, he is. If not...

They cant by law harrass you at work after you tell them to only contact you by mail. That is the way to handle them. If you have an answering machine make sure it is on and recording when you tell them so you have proof. If he is under 18 then you will be responsible. If he is 18 or over then he is responsible. If you have any other questions, look up credit laws at your local library.