Xiaomi India — Redmi note 4, 3g, 4g network problem

Address:

Nadia, West Bengal, 741501

I bought redmi note 4 mobile about four months ago. A problem has occured on this set i. E. 4g, 3g network problem.
I gave it nearest service centre, ranaghat service center on 21st june, 17. But today 4th july. They told that set has not repaired. Also told that a parts requarement mail to head office has been pending. So that parts has not reached.
Please solve this problem. This mobile set is very usefull for me.