The critical issue is likely whether it is the creditor him-, her-, or itself going to your place of business, or whether it is third-party debt collection (e.g. collections agency). There are some fairly stringent limitations on what third-party debt collectors can and cannot due; if this was a collections agency, there is a good chance it could not do this. (Look up the Fair Debt Collections Practices Act, or FDCPA, to see the restrictions.) On the other hand, there are very few restrictions on what a creditor can do to collect a debt owed to that creditor--they can't defame you (make untrue statements of fact which damage your reputation), harass you, threaten you, etc., but may well be allowed to go to your place of work to confront you.