I have attempted to use my presale code to purchase tickets for the Auckland U2 concert. I entered in the code ok and chose 2 standing tickets. I then clicked on "get more tickets" (as I wanted to buy 2x PI7 seated tickets). This took me to the page requesting me to enter in my presale code again. I did so but it would not accept -showing "Incorrect. Please try again". Subsequent attempts using my code brings up the same message. What can be done so that I can use the code?