Repetition is key. I have a job where I regularly brief a large group of people every day. At first it was hard, and I was embarrassed and struggled, but now, it’s as easy as singing a song. Don’t give up. My dad told me when I was a kid to never let your stutter control you. It took me almost 30 years to understand what that meant, but I don’t let it stop me from doing anything. My wife used to order food for me, now, no matter how long it takes I WILL say what I want. I understand that you are selling yourself and a service, and having a stutter can be difficult it those situations, but don’t give up yet.