Well, it's official now. My mortgage has been approved, everything is taken care of. The official transaction will take place tuesday next week, at 10 am. This is 11 days after the planned date of transfer, which means that I'll have to cough up 225 Euro interest. All of this because some silly financial institute made a goofup and had to think way too long to figure out that they wanted to charge me with an additional 3 euro per month for the next 30 years.
So the price of being overweight can be calculated exactly now: 30 * 12 * 3 + 225 = 1305 Euro.