I work in the hospitality industry (I sell facilities for conferences, dinners & weddings). I have listed my standard cancellation policy below (these are pretty standard across the industry):
Where the cancellation is more than 48 hours before the event:
90% of the charges for cancelled accommodation and room hire,
80% of the charges for cancelled day delegates package rates,
65% of the charges for cancelled meals, drinks and other facilities and services.
If you had to pay 50%, it would not be too bad but on the other hand, if you have not been made aware of the cancellation policy – you should not really pay anything.
Hope this helps.