I did this years ago, though not on the same scale as $18,000.  I switched internet providers, the previous provider continued to charge me, but because I wasn't reviewing my bank statements, when I discovered it after about 6 months, the bank would only refund my account 2 payments.  Now I check my account online once a week.

Check your accounts almost daily.  Latest billing scams are automatic renewals on subscription magazines and virus software.  Got a $44 charge from Norton for out of date virus software on a really old computer not even being used.  Also, watch magazine subscriptions.  You may get the a cheap intro price of $8 for a year, but if you pay by debit card or credit card, next year they may process an auto renewal at $30!!  Even after squawking, they refunded $29 and kept $1.  Those items could have caused an overdraft on an account if I had been low on funds.  Companies should not be allowed to do these things.  Where is the FTC when you need them.  

WOW.  That is an expensive learning experience.  I feel bad for the guy, but I don't understand how someone does not actually LOOK at their statement.  

No, the FTC regs are WORSE than that.

This is taken from FTC.gov - the last paragraph is the kicker.

The Fair Credit Billing Act establishes procedures for resolving billing errors on your credit card accounts, including fraudulent charges on your accounts. The law also limits your liability for unauthorized credit card charges to $50 per card. To take advantage of the law's consumer protections, you must:

   * write to the creditor at the address given for "billing inquiries," NOT the address for sending your payments. Include your name, address, account number, and a description of the billing error, including the amount and date of the error. See Sample Dispute Letter for Existing Accounts.

   * send your letter so that it reaches the creditor within 60 days after the first bill containing the error that was mailed to you. If an identity thief changed the address on your account and you didn't receive the bill, your dispute letter still must reach the creditor within 60 days of when the creditor would have mailed the bill. This is one reason it's essential to keep track of your billing statements, and follow up quickly if your bills don't arrive on time.

How many ways can you say DUMB. REALLY REALLY DUMB.

I'm going through this right now but I check my bank records almost everyday and my credit reords maybe twice a month.

I went to pay one of my credit cards on Sept 11 and seen the amount I owed and I couldn't believe it. So I checked the transacton history. Just5 days prior someone made a purchase with my credit card number on the internet for almost $400 and on the very day i found out they made another purchase again for almost $400 and at the same online store. I was  outraged and immediately called the online store to try and get info on this purchase, no help until I file a police report, which I find is ridiculous! I then called my credit card company and told them and I closed the account and told them to send me a new card with a new account number. They weren't going to take the charges off until they did their own investigation and I got a police report.

Police report was next. He asked how they oculd have gotten my number. No one has access ot my cards and I rarely use them and I didn't lose them so I figured that someone may have gotten the number when I handed it over to pay for a small purchase. So he took the info and said they will investigate and get back with me.

My next step is too put a security alert or fraud alert with the credit agencies. I'm so upset but I feel like I can't do anything when I really want to do is beat the heck out of this person who did this