Disputing a frivolous claim of copyright infringement

I received a copyright infringement notice (or takedown notice) from Musescore on May 15, 2019 alleging infringement of a song purported to be owned by Alfred Publishing, and I filed a dispute report (or counter-notice) with Musescore on the same day. It is now August 3, long past the 10 days Alfred is required by law to reply, and I have heard nothing despite repeated emails to copyright@musescore.com The score in question is my original arrangement of a melody that is in the public domain (an old Stephen Foster tune). I believe that Alfred sent the takedown notice recklessly, probably automatically and based only on a partial title match. Because they and/or Musescore refuse to respond, I do not know which of their scores they even claim was infringed (and it is unlikely that they know). I understand that Alfred Publishing was obligated to respond within 10 business days of my filing the dispute, and that access to my score should have been restored within 14 business days of its filing, according to Musescore's statement of procedure at https://musescore.com/legal/dmca. Does anyone here have experience in filing dispute reports, or experience in getting Musescore to follow their procedures with respect to dispute reports?