Baseball question from a football/basketball ref.

[gordon30307]

I was doing some college wood bat this summer and the the count was 3 and 0. The batter stepped out of the box and asked me to open up the zone. I said OK. Next pitch was high and I called it a strike. The 3 and 1 pitch was higher and I call ball 4. He looks at me and I tell him sorry no way that I can call that a strike. A first for me a batter complaining about balls.