My first suggestion is don't keep a "backup" funding source on any bank's website. Very few people do that AFAIK, and so there's not many data points about whether such mistakes can occur at other banks too. (You can add a new funding source quickly if you need to for a special situation, your can just "push" a bill pay from your checking account to the credit card if you need to, etc. No point in setting yourself up for this kind of problem by permanently setting up a "backup" funding source which you don't actually want to use.)

And my other suggestion is don't confuse "customer service" in general with your particular unusual situation. Even banks that have better "customer service" in general may sometimes not do well at it.

So if you follow my first suggestion above and set up your account so a mistake of this type is not possible, I would recommend you look at Citi AA Plat, since it's also an AA card, which Aviator is, and also has 0% forex, like Aviator has.