Refuses Refund

My mom booked this venue almost a year ago I think it was for her wedding, she was very excited and loved this venue and the services they offered. She paid almost 20k (I could be mistaken on the exact amount though) in order to book this venue for Friday the 13nth (bad day for a wedding but thats my mom), unfortunately things have happened since that caused my mom to cancel the wedding, she contacted the venue to notify them of the cancellation (18 days before the wedding) and they have refused to refund her 1 cent for the venue? she paid in full, she did not pay half as deposit or anything like that, so the venue will stand empty on that day (as im sure it would have in the first place) and yet they refuse to refund her 1 cent of her money, she is not expecting a full refund as that would be unreasonable but a 50% refund on services you are no longer offering should be standard right? this is ridiculous and is day light *******