@Carrie389 Did you read the information for guests in the Airbnb Help site which tells guests the protocol when they arrive to find a place unacceptable?
First you need to notify the host about the issues, affording them the opportunity to rectify the situation (for a cleaning issue the host could send their cleaners back in to do a proper job).
If the host is unable or unwilling to address the issue, you contact Airbnb within 24 hrs. after check-in to report the issue and cancel the booking, and you will be refunded as long as it's legitimate.
Battling with the host about a refund is what you don't do. Hosts aren't even paid until 24 hours after check-in- until then, Airbnb has your money, not the host.
Failure to follow stated procedure can make it difficult to get a refund from Airbnb, but at this point all you can do is contact customer service and plead your case. Good luck.
P.S. No point talking to Airbnb about the illegal subletting- they don't care or keep track of those things- that's a matter between the subletter and the owner. Concentrate on the unacceptable conditions of the space itself.
I'm not sure what you mean about being "placed" in this listing. Did you not book it yourselves?