The problem is the description of General Helmuth Reymann as "Volkssturmkommmandant" of Berlin. That title is incorrect: On March 5, 1945, Hitler appointed him "Kampfkommandant", i.e. overall military, or fortress, commander of the city to replace Lt.Gen. Bruno Ritter von Hauenschild who had fallen ill. That position put him in charge of all units, regular Wehrmacht and Volkssturm (not Waffen-SS though) that were garrisoned in Berlin, such as Wachregiment Berlin, replacement battalions, Flak batteries, depot and training school personnel, recuperating men from army hospitals, Polizei, RAD, Hitler Youth, etc. The bulk of these local Wehrmacht units had already been transferred East to bolster the depleted German divisions that were desperately trying to hold the Soviet armies on the Oder 50 miles away. Thus it was a pathetically small and totally under-equipped force (some 41,000 men), having no tanks or heavy weapons, with which Reymann was supposed to defend a defensive ring around the city between 24 and 36 miles in diameter - clearly an impossible task. It was only after April 16, 1945 when the remnants of the various German armies retreating toward Berlin reached the city that there was the semblance of an effective defense. On April 23, Hitler replaced Reymann with Lt.Gen. Weidling, CO of 56th Panzer Korps, as Kampfkommandant of Berlin. It was he who surrendered the city to the Soviets on May 2, 1945.
The Volkssturm was formed in October, 1944 by order of the Führer under the aegis of Dr. Goebbels and was organized by local SA and Party leaders, but ultimately placed under the command of the Wehrmacht. In Berlin the man responsible for raising Volkssturm battalions was the chief leader of the Berlin SA, SA-Obergruppenführer Graentz, but he had no powers of command and worked with and under Reymann. It may well be that HE is the mysterious "Volkssturmkommandant" referred.
The Last Reserves: Political-Military Aspects of the Structure, Function and Composition of the German Volksturm, 1944-45, by David Yelton, as a dissertation through Univ-NC Chapel Hill 1991, DAI 1991 51(10)L 3498-A. DA9106154
Army of Despair: The German Volksturm, 1944-45, by Burton Wright III, as a dissertation through Florida State U 1982, DAI 1982 43(6): 2062-2063-A. DA8225315