Cello World - Low quality product delivered denied warrenty

After one month of recieving the bottle, it stopped keeping the water warm, contacted customer care, and sent pictures and videos. They said, they can not open video and only picture can be seen, since the bottom of bottle is shiny, a slight dark shadow came, they said it is dented, but later I send more than ** images where there is no dent, but they are fixated on the first image and denied any help, nor they are giving higher authorities phone number, now they are not replying the mail, and on call also no help. They are not sending a technician or giving an address where I can go and show the bottle