Tiger Direct Tiger Direct overcharges and then refuses to do aything about it Miami, Florida

Hello,
Most recently I had a horrible experience with Tiger Direct.  They billed me for $19.99 several months after I placed an order with them.  Their customer service kept repeating to me that they did not show the charge and there was nothing they could do about it.  Right after they get done telling me there was nothing they could do, they actually had the nerve to try to sell me an android phone.  Below is a copy of the letter I mailed to Tiger Direct.

May 5, 2011
Tigerdirect.com
7795 W. Flagler St. Suite 35
Miami, FL 33144
 
To Whom It May Concern:
 
I have been a Tigerdirect customer a few times and have never had problems.  Today I went through the most absurd experience a customer could ever have.  In early February 2011 I placed order #F4728583.  All of the items came to my door as described.
 
Today, I called Tigerdirect customer service to question why I was charged $19.99 on 5/03/11.  I have not ordered anything since February.  Your customer service agent acknowledged that he could not find any charges on my account on his end, but I should dispute the charge with my credit card company.  To add insult to injury, he tried to sell me more items that were currently on sale.  How absurd is it to call customer service to report an error, be told that there is nothing we can do, and then have the same company try to up sell sale items. 
 
You probably noticed my purchase of several antistatic bracelets in February.  You might be interested to know that I teach A+ certification classes, computers, business, accounting, and marketing.  I will surely share my experience with my students.