16 euros is the cause of my stress. I'd transferred what I thought was the correct amount but was short by 16 euros. Because Oldenburg Uni don't do the whole 'confirmation of payment' thing, I didn't know that I hadn't paid enough. So instead of letting me know this directly and allowing me to sort it out properly, they wait till the very last minute and threaten to chuck me out in a matter of days.
I've taken advantage of the opportunity to ask whether I'd get my tuition fees back if I decided not to go next month. It'd be more kerfuffle in the short-term, but I've had it up to the eyebrows with their terrible administration.