Usually you get an invoice a week in advance. Normally If I hadn't received one a few days before expiration, I would submit a ticket through customer service. I did receive mine for this month, so it could be just a glitch. I would contact customer service and explain that you didn't receive your invoice. In the future, always be aware of that day which your account expires so you are on top of it days before and can submit a ticket explaining the problem, preventing the shutoff.
