The bank wants to see if the house is really ready to move into. So whether doors, a kitchen, floors, walls, bathrooms, etc. are finished. For this, the appraiser has to come in. It could be that you have massively overestimated yourselves and are living without doors on the bare screed with a hotplate and a bucket as a sink. If you refuse, there is definitely something in the terms and conditions that says the bank can, if necessary, go as far as terminating the loan. But honestly... where’s the problem? He takes photos and then deletes them again. Every photo uploaded on WhatsApp is far more "dangerous". In any case, I see the bank as being right here. You got a lot of money, earmarked, from them. And now they want to see if the house really has the value you suggested back then to get the loan.