Unusable Charger

When I saw a magazine with two sockets and a power of 2 A, I thought it was absolutely necessary to enjoy it, especially since the comments were very positive overall.
Unfortunately, receipt and use, I had to quickly disillusioned. I tested it to charge my tablet Nexus 10 (with special cable dedicated Pogo) and my phone Xiaomi Mi2. Both devices are equipped with large capacity battery (9000 mAh for Nexus 3100 for Mi2), which explains the interest of a more powerful than the original charger.
After 4-8 hours of charging, the battery level of only rose from 25 to 30%! My usual charger (an HTC Desire comes with my) allows me to fully recharge two devices at the same time ...
If the delivery was carried out in time, I am extremely disappointed with the charger that I will return. The model he received was defective? I do not know, in any case it is absolutely not meet my expectations and is not at all the announced features.
If you order, I wish you to be more lucky than me.