Help with parents???

[bookworm0724]

I have a prepaid Verizon (NYSE: VZ) phone, but because I use my phone so much I want to get a phone with a plan. I've offered to stop getting an allowance and get the phone instead, to pay for the phone itself, to pay the charges if I go over my minutes and pay the early termination fee if they decide I can't have it anymore. I'm 14 and a freshmen in high school, I get pretty much straight A's with a B here and there. I play basketball, I'm on the newspaper staff and I'm class president so I stay after school a lot. I've never really given them any reason not to trust me. I've even picked up more chores at home since I've been asking. They still aren't convinced to do it, what else can I do?