Airtel — excess charge and not fulfil the plan 3+1

Dear sirs, Your bill no. 89169136 dated 27.5.13 u have charged as bill period amount Rs. 302.40 + 2997 for 9Gb/2Mbps for 3+1 plan. activation of 3+1 plan was approximately 5th May 2013. Now I receive a bill No.[protected] dated 27.8.13 for Rs. 1465.49 as for my 3+1 plan was ending 5th september 2013. I don't understand why you charged me now bill period charge Rs.1298 and what happand Rs. 302.40 which you charge through the bill No.89169136 dated 27.5.13 which I paid ? What happand plan 3+1 as you charge me 4th month through the bill No.[protected] dated 27.8.13 ? Please give me detailed explanation and statement from 26.4.2013 till 25.8.2013. Regards Nazir Malime