Jaquar — very slow water out coming from jaquar tap

Address: Mysore, Karnataka, 570028

We installed jaquar diverter set for hot and cold water, but suddenly hot water outcome become very slow from the tap. Hence please help us in fixing the issue, so that hot water comes very faster as before from tap. We complain to many plumbers to resolve the issue, but we can't able to resolve the issue. We also examine the solar company, but they examine and it find no issues with solar heater.