Hopefully this won't happen as you'll get a little 'charges reminder' every month, a few days before your account charge(s) are taken. But if it does, someone from the team will be in touch to let you know you've dipped into a negative balance and to add some cash to bring it back up. If you still have a negative balance 30 days after you've been asked to add cash, we'll have to disinvest you to cover the amount owed.