We get commission where we work, this guy always runs past me and takes my customer. Almost pushes me out of the way what is the best thing to do to stay with the sale/customer?
Trip him while he's walking past? Lol jk
Stop him and say something along the lines of "actually, I got this John. You don't need to help me." and guide the customer somewhere else away from him.
But before you do this, you should confront him about it first.
You should let him know about it. If he doesn't quit it, let a team leader/supervisor/manager or anyone overseeing you both to know.
Get a little bottle of pepper spray. Spray it in face. or maybe a stun gun .