Cancellation notice error

[Phil2731]

I have a long term Air BnB (6 months).  I decided to cancel a few days before starting.  I got a cancellation notice with a charge considerably higher than what my confirmation said it would be.  The confirmation notice said I could cancel up to the 12th of January and only have to pay one month rent and a service charge.  But on my the cancellation email it said I would be charged the entire amount of the 6 month rental period.  This is obviously wrong.  How to I fix it?