@Bianca492 Take a breath and a step back. Have you contacted Airbnb to say there was an error made, that you never cancelled this reservation from your end, and that you specifically said no when the agent called you?
If not, this is the first thing to do. I've read of this happening to other hosts, and the host penalties were removed. It might take some time, but if you are persistent, you will likely prevail.
Do not phone them. Use their messaging option so you have a written record of the exchanges.
And I doubt it would be worth your while to try to sue them for errors or inconvenience.