Background Research Firm Being Unprofessional?

i'd recommend something to the effect of calling HR and saying "hi, just wanted to say how excited i am about the internship and had a couple questions for you." i'd then ask a question about some random thing that i was curious about, and then switch to the topic regarding the background check. i think i'd mention something to the effect of how you understand that someone called your previous employer to do a background check and asked questions X, Y, and Z, and then ask if it would be considered standard procedure. obviously, the fact that you have to ask will immediately suggest to HR that there was something strange about how the background research firm conducted itself, but you'll come across as being polite and curious rather than accusatory. just take whatever they tell you at face value, leave the ball in their court, and let them handle things behind the scenes. chances are, even if they don't tell you what they'll do, they'll probably figure things out internally and make sure tenuous situations like yours don't come up again. i'm sure the last thing they want to do is alienate the contacts and networks of an incoming hire.