Blackberry Curve

I keep having problems with the Blackberry Curve.

One of my hats says "Telecom Manager" and that includes taking care of all of our cellular stuff. We've got a bunch of phones, some of which are Blackberry Curve phones. We got two awhile back, which have worked fine, 100%. Later we got two more, both of which I had to replace within a few days because they would not hold a charge. It wasn't the battery - we tried replacing that. It was the phone itself. Then, a month or two later, we had to replace another of those - replacing the replacement! Because of the same problem.

Now, I got two more of them, one seems to work fine (though we'll see whether it holds a charge or not), while the other works fine, unless you try to set the time, at which point the device reboots. So its two days and a few hours behind.