Over-aggressive employee forces me into accepting his help against my will.

I'm working on a DIY project to create a magnetic wall stand for my phone when I'm in the kitchen. I went to the hardware store to get the parts I need and I was immediately confronted by an aggressive employee from the other end of the aisle who insisted on knowing what I needed. He literally screamed, "What do you need?" I didn't need or want any help but had no choice but to tell him what I was doing and what I needed just to get him to stop yelling at me.

The duress ruined my whole shopping trip, and I don't even know if I want to follow-through on the project at this point.