u/kurtoskalacs455

(Sorry for any mistakes in grammar English isn't my first language) So for context I got a 3 year old rex rabbit and her cage is very small around 100cm in length and maybe 40cm wide . I wanted to get her a bigger cage for a while now but my parents wouldn't let me saying that the cage she has now is perfectly fine and we don't need a bigger one . Does anyone have any tips on how could I convince them to get a bigger cage and what kind of cage? Possibly not the most expensive ones if that's possible