Wonderchef Home Appliances — discoloring of water bottle

I have purchased wonderchef water bottle in a pair with blue and green color set and with a marketing attraction of 10 years warranty. Date of purchasing was 26th aug 2016. After few months i have realized there is discoloring of water bottle cap and raised complaint with customer care. To my surprise one representative visited and could not resolve my query instead asking me that such request can be considered in few months and not after year. I asked him can you show in warranty booklet but he could not. My product is in warranty but why its ignored