I possibly have a related issue.
Four years ago our name changed. I changed everythine I can think of in my old Avaya G3siV11. It still, occasionally comes up with the old name. What I think is happening in my case is that each carrier has a data base (we are served by AT&T) and when a call is made to someone with some fly by night carrier, the carriers data base populates the old name. Not sure this will shed any light on this particular problem.