You're mixing terms now.
"Refill" is a prepaid term, which means if you've had $0 in your account
for 90 days, your account has been closed and there's nothing you can do
about it except re-signup with T-Mobile.
"Bill" is a postpaid term, which means you get a bill for monthly service.
If you haven't paid a bill for 90 days, it means you're in default, your
account has probably been closed, and you've been sent to Collections for
non-payment.