I’ve done more research on this question.
You can’t be forced to pay the Developer’s mortgage cancellation costs, even if it says so in the private contract. The reason being that this would amount to an illegal clause that would be thrown out in court.
So turn up to the notary with all the money you need to buy the property, but not to pay the cancellation costs. If the developer refuses to complete you have the notary as a witness that the developer is in breach of contract (refusing to complete despite the buyer providing all the funds legally required to provide).
By the way, I know you are out there completing today – good luck – but I’d appreciate it if you could get back to me regarding the ‘crime on the costas’ topic ASAP.