@Sean78 I have not heard of this! Are you using Instant Book, or did this person give you any lead time? One of the benefits of NOT using IB is that the credit card should have time to be processed. I wonder, though, if you have requested verifications and host reviews in your booking settings if this would alleviate this particular issue.
I don't know how to help you, but I think it's important to figure out how to keep this from continuing to happen.
Regarding the lack of support from Airbnb, I encourage you to keep calling and be the squeaky wheel if you have to. I find it very frustrating that staff is so unavailable to trouble-shoot problems outside of the normal customer service issues. Calling at different times of the day may help too, because you will then reach different call centers which might help.