Apple India — not yet received my phone

Address: New Delhi, Delhi

I submitted my device twice in you service centre but not yet your executives solve my problem and not return my phone from last 15-20days... I want to know where are my phone from 15-20 days what are you guys doing with my phone, everyday i call twice or thrice in you service centre but no one explain me anything about my phone
I am a apple but now i am not satisfied with your services i am totally disappointed with your service you have totally third class service you charge lot of money for your products but your service is pathetic

Products - iphone 6s
Seriol no - f17qh1sdgryg
Imei no - [protected]
Phone no - [protected]