Did you decorate your house yet? If not you can ask the 裝修師傅 to move down the window. I did it and the effect is goods except that you need to install the 窗花 to hide the hole after you move them down.
If you do not want to install the 窗花 you have to ask how they can cover the hole. Do not trust them to use 玻璃膠 to cover the hole because 玻璃膠 cannot be painted (I have confirmed this with my 窗花 company.
By the way I think $500 to move down the windows only is rather expensive. Try to ask your 裝修師傅 to do it freely for you. My 裝修師傅 moved the windows free of charge.