Instruct: Classify a review into positive or negative sentiment.
Query: I don't understand how some of you don't have problems

I have five of these phones and a base unit. Without exception, each unit's battery gave problems within a few months. (And I did charge each of them 15 uninterrupted hours when starting and whenever they requested it.)Now some won't light at all. On some the battery only goes up to 1 out of 3 bars. On others, it starts at 3 bars but drops to one bar about as quickly as you can get it to your ear.If someone has a solution, please hint at it here.