Airtel — deactivating services without valid reasons

Bharti airtel activated first mobile no on 10 oct 18, second on 12 oct 18 and amazon prime video on 29 oct 18 as per 649 plan. They generated bill for period 26 sep - 25 oct 18 with charges from 09 oct 18. I asked them to generate bill from period 09/ 10 oct 18 till 31 oct 18 and thereafter from 1st to last date of month. Also, i asked them to credit my second no balance amount which was airtel prepaid to postpaid change, as per their scheme. The call centre saying cant help and the nodal and apellate officers mobile and email ids indicated on airtel and trai website are incorrect. Have been making emails and calls daily and they promised that they would escalate matter to resolve. However, there has been no response from them for about 10 days and last two days they deactivated services of the two nos. How can they do like this? They are at fault for not having in place a grievance mechanism and dictating their own bill period especially when the mobile was not activated during that time. How can i take legal action against them? Please help.