Well done you, especially as sometimes it is so hard to go against what our parents believe. I say this as a woman in her 40's!!!!! I know it can't be easy for you right now, but know that you have done the very best you can for your hamster, even going against what your parents believe in, that just shows courage in what you believe in.
Obviously as I am an adult and have my own place I have not had to go through what you have, but I know my friends and family think I am nuts for having cages the size of 100 x 50cm (I too have the Savic Plaza) They call it hamster disney land and in all honesty one day I would love to have 2 cages even bigger, I can only imagine what the comments would be then
Well done for sticking to your beliefs, I hope your parents anger dies down soon. I know these situations aren't nice to experience. Just also know that not everyone thinks the same, so don't be too hard on your parents either, if they don't get it they don't get it.