If you have a Debit Card or Credit Card attached to your PayPal account, call your bank and tell them to cancel the card and send you a new one, this way PayPal won't be able to charge you, i did this when i wanted microsoft xbox to stop charging me monthly membership as i couldn't cancel it cause they never picked up the phone and the website had a glitch, but if you have a bank account attached to PayPal i don't think there's anything you can do. The only thing i can suggest is go to your bank and talk to them, see if they can stop PayPal from charging your bank account which i highly doubt but you can try. You probably will have to pay the negative balance if you want your account back.