Airtel/brodband
To complain for my plan

I have taken 899Rs. plan but currently running plan is 1599Rs. but i have not appiled for running plan and now i have to pay my bill. So plz tell me what should i do. I am not going to pay for this i have taken the plan i will pay for that only please chek document i summited then please help me out. My connection no is-multiple

bill no.-673080569

bil date-18/jul