This actually reminds me about the time my car got stolen. I had parked it in the parking lot here at work and was basically coasting in on fumes (it was pay day). The car got stolen and the police didn't find it for 4 days. When they called me to come pick up the car at the spot the thiefs left it at, I was worried I was going to have to call a tow truck cause it would have definitely been out of gas. To my surprise, the thiefs filled up my tank! Only suffered a broken window and some trash in the car but all in all it worked out haha.
As for your issue, that is incredibly strange! Are you the only one on your account or do you have friends and family on the account as well? I know on my account my parents log in and pay their own portion of the bill. If you are the only one on this account and received these sort of messages, the fraud reports are definitely the way to go. We take account security seriously and will make sure to clear this up for you. I know you already set up a pin on your account which is a great move but you can also check out our Protect yourself from scams document for some additional measures.