Best answer by Dennis
1) Using your number to make harassing calls - Someone could have spoofed your number. Totally possible
2) Hack your facebook or email - Could have used social engineering or had physical access to a device that you were not logged out of. Also possible
3) Change your contact name on other people's phone - They would have needed to gain access to each person's online contacts (like gmail) or had to physically change your contact info on each of your friends phone. Seems rather unlikely.
-If someone has your info, there is no way for any one to know who is sharing it.
-In your phone app you can set it so that people on your contacts can call you
-Changing your phone number does not prevent others from getting into your facebook or email account. You need to change those passwords right away. Start with your email since all "forgot password" links end up getting sent to your email.
-I assume the payless points card is not a credit card but just a loyalty card. It is weird that they would change the name unless they wanted to use your points. Do you have an app that consolidates all your points cards?