Someone has opened a Boost Mobile line using my email address

A couple of months ago, I got a couple of emails thanking me for signing up to Boost Mobile, which I never did. I've been trying to find out what is goin on but the emails area addressed to some with a different first name to me. I have since got a couple of emails telling me my payment will soon be taken. No money is ever taken from any of my accounts, and I actually just genuinely think someone has mistakenly typed my email address in when they signed up. Anyway, I have contacted Boost and they ended up saying I now have to go to all these third parties to open cases for investigation etc,which I honestly don'y have time for. I've already had to spend hours with them trying to explain the situation!

As they aren't able to help me, I am now considering just signing in to the account with a forgot my password link and then canceling it or seeing how I can manage it in there. Is that fraudulent on my part? Or, can anyone suggest a better way to go about this?