@Joerg,

I post this here, as it may be of interest to others.

I received my voucher, and have already made my pre-order for a complete device. All went fine and smooth.

Now, my voucher was bigger than the pre-order amount, so I receive a new voucher automatically with the remaining amount. I then went put 120x "Down payment top up" and put my voucher code (which is for EUR 20). When I hit "OK" I get "There is 1 error. You have not reached the minimum amount required to use this voucher".

I don't know why there's a minimum, nor the value of it. I can just make top up ignoring my voucher, but it might be useful and informative if you (plural you) can explain how this should work?

Thanks and keep up the good work!