How to talk my mom into buying me a pelham?

how old is the horse and how long have you had it and how long you been riding it? because if under schooled then you don't want to be sticking a stronger bit in as it can numb the horses mouth and make it stronger to handle. my horse does that with her bit but its because she needs more schooling and not really used to the bit as shes an ex racer and when i bought her she hadn't been ridden for 6 months that's a different style of riding to what she does now