R.C.
I've noticed that some children who whine improve when they are asked (with a smile) to say the same thing again with a smile. (It's impossible to smile and whine at the same time.) Then the child repeats the request/comment and I thank them for the great voice (never mentioning the whine) and proceed to respond to the message. This can be a fun game, and some children change their whole mood, given the opportunity. Best of luck!