Due to error on web site I was charged for 4 seats for the same flight. Didn't get my money back.

I was trying to book flight form Jakarta to Singapore on Jetstart web site. After entering my credit card information finish the transaction, a prompt came out saying "There has been an error in transaction, please try again". I did, I tried totally 4 times and all the time same error. I did not get any itinerary by email or any other means. I just forgot abut it and booked flight with another company on the same day.
Then when I looked at my Credit card statement later, I saw 4 transactions, totally over $400 dollars being charged by jetstar / actually valuair that was the operator of the flight. I called Jetstar customer service and they assisted me to file a complaint. After about 2 months they sent me letter that my complaint has not been successfull and I need to pay for all the 4 seats.

The referred to the following clauses in their terms of use:
"When you have requested for the itinerary or other flight-related documents to be sent to you by email, fax or other forms of electronic communication (including mobile messages), failure to receive it does not constitute an unsuccessful booking. A booking is deemed successful and complete after payment has been made and approved. In the event of any dispute, the booking in the Jetstar Asia database is the primary record of carriage, and will prevail.

Jetstar is not responsible for the delivery of any electronic communication. If you have any queries regarding your booking, please contact Telephone Reservations or your travel agent.".

So, does it really mean that if I even see a prompt on the web site asking me to try booking again, they still are not responsible for that?