phone won't stay off or keep on vibrate...sometimes

My daughter has a problem with her Storm. She got it the beginning of Sept.-09. Recently she went to Verizon cause the phone wouldn't turn on. They made her buy a new battery. Worked for 1 day did the same thing. They got a new Storm, tried her old battery, (did not work) and then put her new battery in it, (worked) (personally I think she should not have to pay for her new battery since the old phone died right away with the new battery, only a month and 1/2 old). But now, if she puts her phone on silent or vibrate (at work) most of the time her phone will stay that way, but occasionally it will just go on sound and if she gets a text her phone will be "singing". I told her to turn the phone off. She says her phone will not stay off, will turn on by itself eventually. Anyone else have this problem with the phone?