Mi — problem in mobile in warranty period

Address:

Panipat, Haryana, 132140

Sir,
POCO F1 mobile purchased in Jan 2019. Mobile has network issue since purchase. It has been shown to MI service center however it is sad to know that after service and rectification mobile started giving more problem. I m not able to download any app through play store after rectification. Lot of conversation carried out through MI personnel but there is only promises done and no concrete action till now.
Pl help to resolve the issue.
[IMEI/Serial No:, [protected]
POCO F1 by Xiaomi (Graphite Black, 128 GB)
jobsheet enclosed.