Avianto refusing to refund my money

I am completely unhappy with their service. Had to cancel my wedding and understood there was a cancellation fee but now they are telling me that the food money and deposit money I paid will be forfeited if they can't get someone to rebook the venue on the same date. I have read the contract and nothing is mentioned about that so they can't just keep my money. Its not like I'm losing R2 000 here. It is over R10 000. This is unacceptable!