Airtel — monthly data quota not credited

I am using airtel for long time. I changed my post paid plan in oct'17. According to the plan every month i am eligible for 4 gb data. But this data is always showing 0 gb and i complain every month to claim the data that is guaranteed by airtel. I have been complaining for the part 5 months and there is no permanent solution. Even i changed sim, reinstalled app 100 times. Still issue is not getting resolved. It has become a routine that i complain to airtel about this issue beginning of my billing cycle. I am really unsatisfied with the way the customer is treated. Also i am surprised a no.1 service provided don't have technical capability to solve this simple issue. Also i see airtel is not worried about the customer. I am not asking anything free. What is entitled to me in not given which is cheating the customer.