I can't change the contour colorbar of the font properties or contour labels!!!

This is my simplified code:

h = axes;
set(h,'position',[0.511805555555556 0.131326949384405 0.393194444444445 0.715458276333789]);
% scatter(x(:),y(:),5,top(:));

% x and y are 2D matrices

[c,h] = contourf(x,y,top','LevelList',[-3000 -2750 -2500 -2000 -1500 -1000 -500 -250 -150 -50 0]);
% set(gca,'FontName','Helvitca')
clabel(c,h,'fontsize', 26) % fontsize remains the default - I've tried changing color etc.. no luck
hold on

ylim([39.87 40.2]);
xlim([7.2 8.3]);
load('mapcm'); % my personal colormap
set(gcf,'ColorMap',mapcm)
caxis([-3000 0])
cb = contourcbar('Location','southoutside');
cb.XLabel.String = 'Bathymetry [m]';
set(cb,'FontSize',16);  % these work fine but..

So as well as being able to change the label properties, I want to seperate the contourbar into 250m interval levels. How do I do this?