Xank.in - Received faulty product

I had purchased xank smart watch vapor w**, it received in time but with a faulty one. As per their guidelines i charged it for * hours, after that it hardly worked for * mins and went off automatically. After switching it on forcefully again the same thing is repeating. Now the condition is went off completely.
I had called to their customer care number several times but always i get a standard reply saying that our technical team will call you but no one has called me till now. I had send them mails but didn't get any reply. I suffered and fed up of calling there customer care number again and again.
Date of item received: **/**/****
Please look into this matter and help me out.