@Gemma241 It is your host's responsibility to cancel if HE is the one who is not available/made a mistake. He will be fined $50 if the booking is some way off & $100 if it's soon, and he will lose Superhost status, if he is one. - But that's HIS fault, not yours! - This will be why he wants YOU to cancel... but why should you have to suffer the financial penalty? You've done nothing wrong!
Airbnb customer services are super busy right now, owing to Covid related issues, and the fact that they recently laid off 1,900 staff.... I would persist in contacting CS, use the messaging, they will respond eventually!
And maybe send your host a polite message to tell him it's HIS responsibility to cancel, not yours!
Good luck!