@Paul5971
sorry you are in this difficult situation.
I don't really have a solution for you but I can perhaps add a little bit of insight.
When your reservation was cancelled, the host would have had absolutely no idea it was cancelled by airbnb because of credit card issues. The host would just get an email from airbnb stating "we're sorry to let you know XXXX has cancelled the booking" ( airbnb use theme generic cancellation messages regardless of why the reservation was cancelled. I know this for a fact because I experienced a similar situation ). The host - for your privacy reasons - would most definitely not have been told that it was airbnb that did the cancelling. The second the reservation was cancelled the dates would have been made available for other guests. If the host has IB book enabled, this could have happened more or less immediately as it is such a busy time of year
In the case I experienced , my guests was sent several emails regarding the fact that there were issues with her card well before the cancellation occurred. Did this not occur with you?
Did you take out travel insurance? I routinely use this over any peak holidays season as things notoriously can go wrong - flights cancelled, and you are left stranded, hotels close down - and in your experience no more airbnb's available. Nothing is ever fool proof.
In these situations airbnb usually work pretty hard to find you alternate accomodation. IF there are no other airbnb accommodations physically available in Cochrane for that time airbnb can't really do much more than find the closest one for you in helping you relocate. However it may be worth continuing to ring them. I think your idea of reaching out the the general community is an excellent one.
Each host can make their own decision regarding refunds and extenutating circumstances. I can see why you feel hard done by, but equally the host has now lost out on income from 21 - 27 Dec through no fault of his/hers. For the record, the host doesn't' yet have your money - that will still be being held by airbnb. You may find the host is willing to come to an arrangement whereby he/she refunds you if she ends up with a booking for those dates but they're not obliged to do that.
You may find it useful to "close" your case with airbnb and ring up adn start over with a fresh customer service person. It's important to be measured, unemotive and very clear when talking to them. Apparently some customers find they get a better service when they reach out through Twitter - using a line such as "stranded for the xmas holidays due to credit card confusion" might be helpful?
Good luck sorting this out.
Other people will no doubt be along shortly to add more advice.