It's not a scam in the sense that people are pretending to be creditors or some such and stealing information.
If you are receiving calls from them, and they are asking for someone, what they're probably doing is something called skip tracing: they've lost contact with a debtor and no longer have a good phone number, so they start looking for phone numbers belonging to people with similar names/last names.
If they call acting like you're the debtor or this is their number, know that this is what they're trained to do. Supposedly, acting this way will put the actual debtor off guard and trap them into the call.
If you are not the debtor they're looking for, hold your ground and tell them that you are not so-and-so, you do not and have never known so-and-so, and you want your number taken off their calling list. They have to do this, even if they think you're lying for whatever reason.
If you still have problems, here is their US site: http://www.us.hsbc.com/1/2/3/personal. There is a Contact Us link above the Online account access box on the right hand side. It includes the customer service line and mailing address for HSBC Bank.