I apologize for the frustration. I would like to assure you that you will not be charged for 12,000 emails sent out. In Constant Contact you are only charged based on the number of unique active contacts held within the account, not by the number of emails you send out. I was able to take a look at the case within your account and it does appear that our support reps are working very hard to resolve this issue. Usually it takes about 3-4 business days for them to find and try to resolve the issue.They will also reach out to you during that time frame. You can always call in to support and check on the status of your case.
Hope this was helpful to you !