At this point when you are losing subscribers in FFXI and are likely facing the potential for an exodus in FFXIV, I don't think you can really handle this issue with kid gloves. Especially on the business side of things. If I were working in Square Enix, I would tell them to drop ClickandBuy like a wet, soiled pair of diapers and find an acceptable alternative within two months, and I would mandate that Paypal be used as a direct payment option.
It's not that hard to set up a Square Enix direct payment account on PayPal.