Just a note to all,
I booked a flight on Continental a few weeks ago. I had a travel voucher and gave the reservation agent the Code and Pin. She was able to verify the amount as she stated the correct amount (and the correct balance that would be charged to my American Express). I didn't look to verify that she did this correctly (on the email confirmation) but will do so in the future. My AMEX was charged for the full amount but I didn't realize it until after the travel had been completed. I called customer care, but they said that since the travel was completed, their administrative and financial systems wouldn't allow them to correct this mistake (and they mentioned that they hoped all customers would view the confirmation prior to departure and contact them if there were any errors). I was told this by 2 customer care managers, and they were unwilling to escalate it to the next level.

Fortunately I reached out to Christopher Elliot (of CNN Travel fame), and he was extremely helpful. He provided a list of contacts (in priority order) and have reached out tothe Director of Customer Care. I'll let you know the result, but don't make my mistake.....always check not only your itinerary, but also your billing. Albeit, I've only had billing mistake happen once and unfortunately, it was with Continental.