Great info re unconscionable conduct Sophea, I agree ACL does not apply here, and if it did, I agree it would not be refundable. Agree more information is necessary however in the absence of such information, and if no evidence/records can be produced to the contrary, the assertions made by Napitupulu that the seller stated the deposit was refundable are certainly enough to warrant lodging a claim, that is in my opinion of course.
If the seller wanted to make deposits non-refundable she should have had Napitupulu sign an agreement to that effect. In my opinion, the apparent informality of the situation gives more weight to the buyers argument than the sellers. Nonetheless, prima facie this is 50:50 and more information is definitely necessary.