The same thing happened to me last month (April) and they also changed my plan from 5GB to 1GB. I called FIDO and they told me they would contact me in less than 72 hours. But nothing yet! They already charged me the phone on my May bill. When am I going to have a solution to this problem?
I am sorry to see that you've had this kind of experience. I can totally understand how worrisome it must be to have any kind of transactions happen on your account if you weren't the one who authorized it. I assure you that we take these kinds of situations very seriously!
If you've already reported this, the case was assigned to a specialized team that is working hard to get everything sorted out and back in order for your account. It's possible that there may be some delays, but someone will definitely be in touch with you as quickly as they can to get to the bottom of this for you!