How to change units in Bode Diagram?

h = gcr
setoptions(h,'FreqUnits','Hz')

% plot a bode diagram
H = tf([1 0.1 7.5],[1 0.12 9 0 0]);
Hd = c2d(H,0.5,'zoh');
bode(H,'r',Hd,'b--')

% Get the figure handle
h = gcf;

% Change the units of Phase from degrees to radians
u = h.Children(2).Children(2).Children.YData;
h.Children(2).Children(2).Children.YData = u*(pi/180);

% Change the units of Phase degrees to radians
t = h.Children(2).Children(1).Children.YData;
h.Children(2).Children(1).Children.YData = t*(pi/180);

% Set the Y axis limits in visible range
h.Children(2).YLim = [-5 0];

% Change the labels of Phase plot to reflect the change of units
h.Children(2).YLabel.String = 'Phase (rad)';