[Resolved]  Eureka Forbes / Aquasure Crystal Water Purifier. — water not filtering properly

i Purchased a Aquasure Crystal water purifier in the year 10. it worked good for 2 year and after 2 years, the 2 catridge's were changed as the water is not purifing properly, later after changing the water is not purifing properly, there is no difference in the purified water and the tap water, the service person is arguing that he cant help with that as our area is not getting pure water, he got some meter with him and checked both the tap water and filter water to see the readings 388 and 365 respectively. i still feel the crystal in the water when it takes into the mouth. where as the earlier catridge's has good filters, in which i hardly find any water crystals when took into the mouth. i still preserve the older filters to show the difference. in case he stick to his saying that water is filtering then i have the older filters which has a good filtering compared to the new one, i can show the difference of both i.e., the new installed catridges and the older one, which they can experience. so i would like to file a complaint with consumer forum kindly help me by guiding me with your useful suggestions. what sort of proof is needed to file a complaint with consumer forum, how can the water be tested, and where it can be tested, kindly guide me.
thanks in advance