Unexplained charge to my credit card

I handle IT duties in a small company and buy many computers for the company every year.  My choice is always Dell.  Our bookkeepers always require a receipt for any purchase made for the company, especially those on company credit cards.  In the most credit card bill were the expected computer purchases from Dell which I had already submitted to bookkeeping.  But there was an additional $20 from DMI Dell Bus Online.  I had made no purchase for that amount and had never received an invoice for it either.  I called up customer service and explained my situation.  While he could see the charge to my company from his end it had no invoice or purchase order associated with it.  So he admitted it was likely an error.  He then wanted the credit card numbers, the banks information a copy of the invoice which I didn't have. A screen shot of the charge from the computer.  Here Dell had made the error and he was wanting me to waste company time doing his work.  The credit card information is in my account.  All any decent customer service team would have to do is reverse the charge.  I asked him to send me a complete email with all he needed from me and an explaination for my boss of why he needs it.  He refused to do that.  Then he passed me to another person without informing them why I was on the line.  This guy started the same routine despite my protests. Three or four people and repeated explanations later I asked to talk to someone at corporate in Texas.  They put back into the phone system.  So I got a recording where it wanted an order number.  I'm sorry, I ordered nothing so I have no order number.  The fifth person suggested that I just have the credit card company dispute the charge.

Wow! Really?  I love Dell computers but this is not customer service by a long shot.  It should have been a simple 10 minute call that would end with the money being returned, a customer pleased that his favorite computer computer did what all good companies should do, and a customer service rep getting high praise from the customer.  This was definitely not quality customer service.  And it says a lot when a company hides their corporate contact information in favor of communications being sent around the world.