khoi another scam, Internet

i booked a ticket with onetravel.com and found that my credit card info was incorrect.  I was sent an email notification to call the company.  I did and they mentioned that my airline ticket is now unavailable, but a more expensive one is.  I said if the credit card was not processed then I don't want to proceed with the booking.  The representative told me because it was my fault for entering wrong credit card info, they will charge me $17.50 for requesting the airline ticket which has not been issued. 

I don't understand how a consumer can be charged for entering incorrect credit card information.  And to what card are they going to charge me? certainly not the one that I couldn't purchase the airline ticket under.

They are truly looking to make money unethically.