Last week I almost had a heart attack. I got my Sinclair gas card bill in the mail. It said my owed balance was over $300! But my panic was short-lived. I noticed that my previous balance of $220 had carried over onto the current bill. I paid the previous balance, but obviously not before the new bill was printed. So, I placed the bill on my desk, feeling rather relieved, and forgot about it. Today at work I got a voice message from Connie at Sinclair Oil telling me that I had a past-due, outstanding balance and she was calling to collect payment for it. Puzzled, I called her back and explained that she was wrong. I had already paid it. I even have a confirmation number from paying on their website. I told her I would call her back when I got home and could find the confirmation number. But, being the patient person I am, I immediately checked my bank statement to see if I could figure the problem out. Sure enough, I found the charge for $220 on the day I told her I had paid it. It was...