Try discharging the battery to dead flat then recharge if that doesn't work send back to where you brought it from your contract is with the supplier NOT the manufacturer.
If the supplier has gone bust or done a runner then send it to the manufacturer along with a copy of your reciept and a letter explaining the problem with the battery and that the supplier has gone belly up
If you ever have trouble sleeping download a copy of the Sale of goods act and have a good read