Thank you for the confirmation, JOSZEF30. We can go ahead and check to see if your device is still under warranty, and if it is we can replace it free of charge. As long as there is no physical or liquid damage to the device, this process would be possible. Would this be an option for you?
Only as a last resort. More often than not it charges correctly, although sometimes it tiakes some fussing with it to get it to charge at the proper rate.
I finally found the issue after it became almost impossible to charge it: both the charging cable that came with it and the one I'd bought in a Verizon store were going bad and needed replacing. I should have remembered something an old friend, Dr. Pournelle, said: Always suspect the cables.