Out of control wont keep balance anymore

Ive had this for less than a year and now its starting to act up. It will listen to the remote when it comes to changing its mode and moving its mouth but when it tries to go forward or backwards it doesnt keep its balance anymore . I know its not me or the flooring its on cause like ive said ive had since christmas last year.....is it still under warranty? How can i get this fixed?