You are using a "FillPro"? In that case you are a masochist. The ONLY place I use those are in decorative fountains and horse waterers.
1. They are ILLEGAL, (just because someone sells them does NOT make them legal), because they have absolutely NO backflow or siphon breaker prevention
2. There is absolutely NO WAY to stop the flow manually if it does not shut off properly.
3. Either the valve has mercifully died, or you do not have enough house water pressure to direct water through the refill tube.