So I purchased the mipow micro usb 2600 charger on February 27th and I'm really unhappy with it. I'll charge it up fully, but only get maybe a 60%-70% charge out of one charge. Is this supposed to happen? I was under the impression I would get at LEAST one full 100% charge out of it - especially since they talk about how you can charge two devices at once. Can I still bring it back or exchange it? I trusted the saleswoman at my Koodo stand, but I could have gotten this much cheaper... or even better ones for cheaper. Any tips? Thanks!