What's next is...don't bother with it. You were misdirected to contact support. That was entirely unnecessary. All you need to do is stop paying. Or port out the number. That's it.
Yes there are official terms and conditions that state that you can contact support to cancel. But you simply don't need to. Just stop paying. This a prepaid service. When you don't pay, it stops. When it has stopped for 90 days then the account disappears. ie. canceled
Adding - I missed the subject line. I was referring back to the prior problem of wanting to cancel.