Psychology in tennis HELP!!! I have a daughter who?

Psychology in tennis HELP!!! I have a daughter who is an excellent player who only started playing tennis seriously last yr at the age of 13. She is a much better player than all the people she has completed against in matches but always loses due to over hitting and getting upset if the wrong call is made (which happens frequently due to how fast she hits and serves) do we need some sort of psychological help for this. what is the best way to get this... books, councilling ??? any help would be most appreciated thanks