Has anyone tried the B12 complex?

Has anyone tried the B12 complex? Backstory: I sell cars. A did a 3.5 year follow up call to a customer who lives in a different state. He was like "Hey, I have a little story for you if you have a minute." Long story short, he said his son developed a stutter and started taking B12 and it almost immediately went away. Has anyone tried this? Or thoughts, comments, concerns? Short bio: 31 years old, always been in sales so obviously I have managed but it does get to be frustrating and embarrassing. My stutter presents itself in a variety of ways - the traditional "block" or the kind where I say the first part of the word twice. Or three times. Or even the one where it kind of turns into a "click", if that makes sense.