Airtel — Broadband plan change without any information

Have been using airtel landline plus broadband for years.in june this yeae my plan was changed from 599 to 899 without informing me and without ny consent. I have called their no 121 hundreds of times but there is bo way you can reach to a person. On everything they send you airtel links. Even on their airtel thanx app there is no way to make a complaint. I have been paying all the bills before due date according to my earlier bills. They are charging me more as per their own wish. I searched for their email id for complaint on net and sent a mail refarding the same. I got a call today after 3 -4 days and they are doing me a favour of waiving rs.200 as if it is my fault. I was told by the executive that its my fault that i have made the complaint late. I should have called them earlier. Well i have called them n no of times but its of no use. They have levied rs..800 on my account on their own. Whereas no one can change the plan without the consent of the customer.I made this complaint almost 5 months ago.There has been no resolution from airtel.All my other bills are cleared except for the irrelevant charges. Now they have barred my outgoing on the basis of their incorrect charges.