@Hilda5 Let's make sure we are clear on a couple of points.
First, I am *not* condoning AirBnB's practices or actions in these cases; in fact, there are reprehensible. However, since they hold all the cards (and money), we either have to go along with their ways, or find another hosting platform.
Second, once AirBnB withheld this money, AirBnB has turned it over to the IRS at some point. If it turns out they did not, then you should consult a lawyer to discuss possible legal options. But I am betting they turned over the amount withheld to the IRS.
To attempt to get the money AirBnB withheld from you returned to you, you must file a tax return in the United States. Regardless of whether you have any presence in the US or not, this is what you will have to do. The other option is to sue AirBnB, perhaps claiming that they did not have the proper authorization to withhold the money in the first place.
I might be interested in joining that case, as many others seem to be ready and willing to do also. In our case, we are a company with a business located in Iceland, own, manage or co-manage four properties, all in Iceland, and are contracted with and paid by AirBnB in Ireland. No connection to the US whatsoever.
We did notice that since we have been fighting AirBnB over this matter, they seem to have changed their practices in that they now allow the registration of a company, as opposed to only an individual, as the owner of an AirBnB account. But since they withheld the tax, there is nothing they can do about simply giving the withheld funds back to you, unless of course a lawsuit is successful. Good luck!