Calling someone by the name they asked for costs you nothing and tells them you listened.

A requested name is a small, clear instruction, which makes it an unusually easy way to show somebody you take them seriously. Ignoring it reads as a decision, because the information was given and then set aside, and that is the part people notice rather than any difficulty with the word. Getting it right requires no agreement with anybody about anything. It is simply doing what you were asked.

Use the name you were given, in the form you were given, shortened or new or otherwise. If you slip, correct yourself and move on without a speech. Then use it again soon, so the correction holds.