Please see attached photo of stat on cylinder and cylinder, if they are good to judge?It could be wired wrong, it could be a dodgy stat or not sitting on cylinder properly. A photo of the cylinder and stat would help.
John raises a good point as well. If the cylinder stat is set to 60°c then the boiler flow should be higher.
Please refer to my last reply to John that how I set the cylinder temperature and boiler heating temperature.