Your credit limit is nothing to do with your bill. Thats how much you can rack up in charges (phone calls, PPV) before they stop your services. You need to clear the outstanding amount of your last bill before they will re-connect you, in most cases.
Sometimes they will accept a "Promise to pay" where you tell them the date the outstanding bill will paid on, but you'll need to contact them direct to see if that's the case. 150 from your VM landline.