Xfinity Mobile Limited Plan trap

This is about Xfinity Mobile – When some one buys a limited data plan, and the usage is exhausted Xfinity starts to charge some unusual charges like $15/gb/month and total it can cost you $300 because they straight away charge for 15 GB.  This happened to the third line which they very well know it belongs to a middle schooler.  Now when they do it they just text, No Email or No app notification which is simply a way to escape from a question that customer has been informed.  I completely see it as an unethical way of doing business.

Please be aware before selecting a limited data plan/basic plan for your family members especially to school going kids who can fall into this trap very easily.

Below is the snapshot of the Plan & charges.

I am looking in to

AT&T or Verizon today.