That's however what we defined how THIS interest works. And you're aware that GolDeliCo is not part of this project anymore, right? The FAQ existed before the painful transfer of payments from GolDeliCo to Neo900.
Anyway we always been clear and open about the interest being NON-ACCUMULATIVE - I can tell for sure since I came up with it and I've been aware of the accumulative aspect and the problems in it from beginning. If Nikolaus didn't mention it on the GolDeliCo website (though I honestly doubt he missed to, alas I got no archived version of the GolDeliCo website at hand to point you at the particular paragraph explaining it in detail) then that's not my or Neo900 UG's fault. Now you claiming "this is not how it works" feels a little :-/
And before yet another misconception comes up: the interest is defined to never exceed the purchase price of the final order (aka number of preordered devices * price per unit). I'm aware that this starts to get unfair to those who were in with a higher amount from beginning - sorry for that.
On a sidenote: interest is what drives up the number of devices we need to build, to reach a break even. Even though I'd like to - I have no private fortune (except my personal prosperity and time) I could sacrifice on this project to compensate the economical aspects