Lenovo — Zuk z1 network issue

Address:

Rangareddy, Andhra Pradesh, 500060

I purchased my mobile through amazon on 21/07/16. And it got network issue and signal is not updating in mobile. So, i gave it in service centre on 4th oct and they returned it day before yesterday, but the problem is still not rectified. When i called the service centre regarding this issue, he asks me again to bring the mobile to them. It is 35kms far my home, how can go these many times. And the service centre technicians are also not so responding. Today i went again to the service centre, he says irregular matter and he again took the mobile and gave a manually written copy and he was unable to say in how many days he is going to return my mobile. The service centre name is satyam electronics, lenovo authorised service centre, chaithanyapuri mobile no of client :[protected]. Please ask them to repair my mobile or else refund.