Why did the IRS change DD to mailing a check after receiving a 4883C and verifying routing and checking (none of the 3 exceptions apply either)?

I spoke with the verification agent (didn't know). He sent me to accounts mgmt (didn't know). That agent tried to find a supervisor who will now call me back. Everyone says they can't change it, but who switched it from direct deposit to mailing a check in the first place? And why can't they change it when it is a mistake they made?