I have a samsung galaxy tab 2.10 which is about 10 months old. It takes longer and longer to charge the battery - now it takes about 10 hours or more, plugged directly into a power socket using the correct cable that came with it in the box. I have also tried borrowing a friend's (correct) cable and that does the same. I've tried 'calibrating' - ie letting it discharge right down past the point where I get a 'low battery' warning to about 10 or 12% and then charging fully up, but this has only made a very minimal difference. I've done this 3 times. Before I did this it was taking almost 15 hours to fully charge. Should I take it back to the shop where I bought it as it's still under warranty?