Once you really get in your head about not being able to say a certain word, I think desperately trying to force it out can be exactly the wrong approach. Have you tried 'stuttering on purpose'? Go to the counter and intentionally stutter on the word. Your goal isn't to say the word, but instead to intentionally stutter in a more mindful way. Nobody dies if you can't say the word, it's not as catastrophic as it feels like it is. For me at least, this technique helped me regain a sense of control. You could intentionally stutter for a while, and then show a photo/the name. If this is your plan from the start, you might feel more in control and less frustrated.