Find a trainer in your area, Does she like to chase a ball or toy?
Jo, my 2yr old gsd, was stubborn about coming on call if she was interested in something else, so we started playing a "Jo come" game. My husband would be on one side of the yard/room and I would be on the other then one of us would call her. Right when she reached us the other one would call her... we would do this over and over with the occasional other command (down, sit, etc.) to make sure she was listening. She LOVED it and she got tons of exercise. Now she comes every time we call. We still have to add the occasional "hurry" but she is much better now. Good Luck!!!