I am trying to book from SFO-SIN round trip and using a mix of miles and cash to pay for the ticket. When I try to pay I get this message "We cannot process your request right now. Please try again with another credit/debit card, or payment methods if available, or get in touch with your local Singapore Airlines office." I tried different cards and different browsers and the same message still pops up. Gave their customer service multiple calls and was hit with long wait times and staff who told me contradicting information. One told me I was unable to mix miles and cash on the flight - but gave no reason as to why, another told me I would have to go to the redemption center and would escalate my call. Waiting for a call back from them, I was told it would take 2-3 days. Has anyone ever encountered this before or know why my payment was unable to be processed?