How to convince my parents about getting me a horse again?

OK, i am 13 years old i have been riding and working at a barn these past few years and i got a horse named misty back last winter. My parents thought she was really spooky(a horse bit her in the and she bolted...) so they sold her a month ago. and my mom wanted her own horse so she got a sweet mare named sunny. well after we sold misty my parents thought sunny could be my horse but then she sold sunny because my instructer rode her once and she was "forward" and apparently "too much" for me even though i never even got to ride her. Well the plan was to get another horse for me to do shows with this summer and go trail riding with my friends. Well now my mom barely lets me have one lesson a week because "horses are dangerous and nothing but trouble" and she doesnt want to get me another horse again and claims she is "done with horses" (my mom did have a very spooky horse when she was my age) and its really pissing me off because my dad wants me to have my own horse and ride, but hes powerless over my control freak mother. what can i say to her? i mean i have freakin EVERYTHING for a horse, a barn to board her at, 2 saddles, 2 bridles, brushes ect... And money isn't a issue trust me but how can i get a horse back into my life?!