@Kurt-And-Sheila0 The guest has been in residence since early January, and you only noticed in the middle of April that you hadn't been paid for anything but the first month? And yet kept letting the guest extend? I don't know what to say, except that's pretty lax bookkeeping.
I guess all you can do is keep at Airbnb and if they don't come through, then get the guest to pay you privately. How do you know he's tried repeatedly to get Airbnb to accept his credit card? Just because he told you that? Perhaps it's true, but I wouldn't have let this guest stay past when you didn't get paid on time- the credit card problem should be the guest's problem to work out with Airbnb, not your problem.