do something before filing MTR

既然你不在乎多花銀子，且慢。在開支票要求MTR之前，你不妨先做二件事：
1). Call the service center tomorrow denial notice sent from and request to correct error. If rep can't do that, request to talk to supervisor.
2). Meanwhile send additional evidence, REF notice with letter indicating correct response deadline.
Usually filing MTR takes long time. Why don't try 1) and 2) by yourself at first and keep checking web site or calling USCIS for your case status before filing MTR. If the error is fixed, it can save your a lot of time and cost. Otherwise then file MTR by response deadline.