Did you consider your parents side of the story?
Do you know how foul a house will smell without the proper care of an animal such as a cat or dog? Dogs don't use litter boxes or toilets, and it's either you or the parent who cleans up the poo. And unless you are the ultimate dog trainer (Which I assure you aren't) your dog will end up peeing on the carpet and over time that requires steam cleaning which is a pain in the neck. Do you know how much animals cost? A kitten can be $200 and a dog can be up to $2000 (that's for a purebred, a designer dog would probably be more like 200-400, unless you plan on adopting from a shelter). You have to get the animal neutered, vaccinated, licensed and given a check up every year (Plus extra medication monthly. Do you know how costly that is?). Scheduled grooming is absolutely necessary, because they clean your dog in ways you wouldn't even know existed. That isn't free of charge and the pet isn't magically transported there.
What if your parents simply don't want another animal? What if they think that you don't care for your current pet very well, and assume that another pet will be the same story? Another grouchy, mean dog in the house? No way. And, normally, the only reason dogs behave like that is how they were handled in their childhood.
Your parents loved you enough to get you your first pet, and now, all of a sudden, because of one minor decision, your entire life stinks? And it's ALL your parents fault? Harsh.