This is what DOL told me as well, for the 2015 filing. I may try "kicking it upstairs" when I call back again.
If they don't fix this nonsense, we have several plans that will be in the same situation in a couple of years. Have you pointed out to the DOL that filing a final 5500 for the old plan name would include falsely indicating that a resolution to terminate the plan has been adopted, falsely indicating that the plan has no participants and no assets at year end and falsely indicating that all assets were transferred to another plan? The 5500 is signed under penalty of perjury. In most cases, I would comply with whatever nonsense the DOL or IRS representative wants just to get the matter closed. But, not with something like this.