Just Energy Hassled by computerized call that doesn't say who they are and why they are calling, to cancel service I have to pay a $50 termination fee new york, New York

In my old apartment I signed up to use just energy through national grid,  I closed out the account through national grid months ago and moved to a new apt.  Today I was aggressively contacted by an automated computer from an 800 number saying I was required to call a number with my account number given to me on the phone, but the reason for the call and not even the business identity was given, I thought it was a spam call.  I called the number and it turned out to be justenergy asking for my new information, I didn't want to give it to them and they want me to pay a $50 termination fee.  The call eventually ended with it in play that they will send me the $50 invoice to close out the account.  It all seems fishy,  what should I do about this?

thanks