Cancellation fee for cancelling kitchen?

I am an expat in the Netherlands and last year me and my partner went to look for kitchens. At K. we got a quotation from the seller and he said we can block the price in case we want to buy the kitchen in a year or something. Then we asked if we can cancel it later. He confirmed that we can cancel anytime without any obligation. This he said with certainty and we believed him and signed the agreement. After a few days we informed the kitchen company that we don't want to buy the kitchen, however after several attempts where we tried to explain them the situation they are asking us to pay 30% cancellation fee. We have sent them several emails and phone calls that we want to cancel the kitchen and since we clearly asked if we can cancel it before signing. Also the document does not have it mentioned clearly that we need to pay cancellation fee rather it redirects to website for terms and conditions. Also the document was in Dutch so we could not read it at that moment. So could you please suggest what can we do in this situation?