I am truly sorry this happened to you. It's not a good introduction into ball pythons. I understand about only having room for one. But be warned, they are very addicting and it's hard to stop at one!
I would do my best to convince the breeder to take her back, but be forewarned it doesn't seem likely at this point. If you have your heart set on a mojave, at least they are easy to spot!
I wish you all the best, regardless of what happens.
Gale