t-mobile dash. battery or phone problem?

[Elizabeth]

I purchased my dash in october of 2008. I had numerous problems with it and t-mobile finally sent me a new one last july (2009) claiming that it was my phone that was bad and had nothing to do with the battery. I have had the phone a little over eight months now and have been having even worse problems than before. They started a few weeks after I got the phone, but t-mobile insisted they couldnt do anything about it. The phone shuts off every five seconds and will NOT turn back on. This also happens when its charging. When on the charger, it will not charge and when it does, it will not hold the charge. I end up having to leave my phone charging all day just in case i get a phone call, even then it shuts off most of the time. Keep in mind that the charger is brand new. Other problems include buttons not working, screen freezing, its so slow, volume button doesnt work, alarm goes off randomly (if at all), text messages and calls not being received, cannot retrieve contacts, cannot make phone calls, phone will not answer calls, and pretty much everything else you can think of that goes wrong with a phone. I do not have internet and I delete messages when it lets me. I have taken it in numerous times and this last time, they told me that it was the battery and not the phone, but that they didnt carry that battery in the store anymore. Has anyone had similar problems? and if so, was it the battery, the phone, or a contribution of both? I dont want to buy a new battery if it wont do any good. and tmobile told me that i could upgrade early, but that i can ONLY get a smartphone...which is way out of my price range plus i would have to add internet for $30 a month, when i dont even need the internet. i dont know if it would be easier to get a new phone, new battery, or just change my network provider. tmobile has been great, but they will not help me at all and every single phone ive bought from them has had a problem.....i went through 6 razors in the past two years.