I'm Erik D. Magnus, and both my titles in Sound Department of "The Working Dead" 2013 has been attributed to Erik H. Magnus. He says he has contacted about getting it changed, but that I needed to contact as well.
Anyone can make the change, but if he has done it then it'd be best not to submit any further changes - the problem is I don't know who he has contacted or what they have said or if he has made any submissions to fix that. Do you have any further details?
Are you credited with your middle initial on the credits? If so it is an easy enough to prove and fix.