Windows are smaller than in the building application/work plan.

Hello,
we have a problem with the windows in the new building. Unfortunately, the deviation was only discovered after the house acceptance. According to the building application/working plans, the windows should be 6 cm higher (larger) than they currently are. The parapet height is now also 6 cm too high. This annoys us greatly, as this height was a compromise and I would have liked even larger windows......
Does anyone have tips on how to proceed?
Thank you very much

determined after the house inspection

So you formally accepted the too small windows as free of defects?

We noticed it shortly afterward.

We noticed it shortly afterwards.

But you accepted them free of defects in the delivered size. Which defect do you want to claim now?

We assumed that it fits. Unfortunately, we did not double-check everything.

Well, that's just how it is. A bit too small and too tight can sometimes look quite nice.