Motorola Solutions — moto e4 (plus) calling problem

Address:

Indore, Madhya Pradesh, 452010

I am from indore (Mp). I have bought moto e4 plus in july 18. After 15 days i face problem of auto switch off and not get power on normally. I went service center (Gayatri incorporation) to repair it. Only software update was done by service center.
I left it 7 days for testing but no testing have been done on my mobile. I went to service center of as on[protected] evening) i instert sim card. Both card was not showing network. They took it again and did repair hand to hand. And gave me phone.
Some screw was not fixed in my mobile.. Back side was slightly cracked because a screw was over tighten by him. (It came to notice when i open back cover at home)
Now second day problem arise when i am calling with that phone caller is not able to hear my voice. Voice get slow after 1-2 minutes.
I again go to service center. To tell fix this new issue on[protected].
They fixed screw before checking what the exactly problem is. Service centre is not accepting that there is such problem in it. I am facing problem since 7-9-2017. No one is responding proper. I called many time at customer care also. Lastly i talked to mr. Rahul as on[protected] he also gave me reference no.[protected] and told me senior will call you lastly as on[protected] but did get any response from your company..
Neither customer care is helping nor service center is giving any solution for this problem.