I used to work at a gym making contract sales. Worked there for years. I had to answer phones and make conversation with customers. The place was called "Fort Fitness" so on the phone i would have to say "this is fort fort fitness how may i help you" it took a few weeks but i got it down to where i could recite the quote on command without any issues. Then after three years they sold it and changed the name. I couldn't get the new name down for months. Eventually getting me into a fight with the new manager who mocked me for not being able to say it. Things like "spit it out" or imitating my stutter. I got tired of it and we got in each others faces during peak hours screaming at each other. I ended up getting fired over it. But he got his and ended up getting fired Few months later for arguing with the owners. But much like your situation i worked at a subway for a short while in high school and ended up quitting because i couldn't speak to customers comfortably. But that manager was cool about it and understood