Unauthorized Air Drop Contact when Contacts Only is selected

I have ALWAYS selected to only Air Drop with my Contacts Ony. However, recently an unidentified iPad has started appearing. A few months ago (October 6, 2016) I received a pop up bubble notification that my Apple ID and phone number were being used for iMessage on a new iPad under the name of my husband iPad (3)... we don't own three iPads! Needless to say, we quickly changed our password and meticulously scoured our Apple receipts for any fraudulent activity. Nothing popped up so we dismissed the "bubble warning". A month goes by and I noticed that while I was sharing my personal iPhone hotspot (with one of my iPads), that another unauthorized user seemed to be piggybacking off of the signal. So I shut off my phone's personal hotspot (& all of my devices). Fast forward to this month and I have noticed that another (or the same) unauthorized user is popping up periodically whenever I try to Air Drop (remember I have always only used the "Contacts Only" option). Also, as of today my new iPhone (7+ 128G) is no longer registering as my phone but as one of my newer contacts phone whenever I try to Air Drop from the iPhone to one of my iPads. I have since deleted the contact but my phone is still registering under their name! I do have a few screen shots that I have taken as documented evidence (in case it is a hack). However, when I tried to post them to this post, no option was available for me to add the screen shots.