I was trying to book another ONE3 RTW (ex-ICN) by using booking tool. The 1st sector is on Japan Airlines and Qantas is issuing the ticket.

I got an email from Qantas Seoul saying they cannot accept my AMEX card without my own signature. I have 2 options :
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1. You can bring AMEX card with the card holder and stop by our Seoul Qantas office. Then the card holder can directly sign on credit card bill.

2 . Or you can give us another credit card number to issue your ticket. Diners, Master or Visa will do.(should be your card)
And we have one more thing to ask before issuing ticket.
We feel really sorry to bother you but we would like to have a copy of your passport and a copy of your credit card for security reason.
It’s not about passenger’s credit or something but it’s our policy to have some documents when a booking is made through website and especially when it’s pretty huge amount of ticket fare. Please scan them and send it back to may e-mail.
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I can easily pay by VISA card.
Now, may I ask if it is a common procedure to send them a copy of my passport and credit card.

In my itin, all the sectors are on CX and BA plus a short flight on JL, no QF at all. If I need to change the itin in the middle of the trip, which office/airline should I contact?

I have another STAR RTW (ex-ICN) ticket issued by Lufthansa earlier and had no problem with my AMEX card.

I would appreciate any comment from the experts here! Thanks.