Location/place: vashi navi mumbai

Name of company/service: vodafone

My bill for the month aug-sept is Rs2043.According to the data provided by the staff at the vodafone store
out of the Rs2043, Rs1800 has been charged for internet usage.On the 11th of august I had activated the scheme of
VMC199 for 1.5GB by sending a message to 111 .I have recieved a reply stating that
“Your activation request for VMC199 has been registered successfully.”
The internet connection was however not activated and on 12th aug I called the customer care to activate the the above scheme
and i was told to send the same message to 111 which was ACT VMC199 and the connection would start in 24hrs .The call id no is 442265072
I followed the instructions of the customer care,to which I again got the same reply that my activation was successfully registered.
Within 24hrs I could access to the internet.Now vodafone has charged me Rs1800 for internet usage saying that the scheme wasnt activated.
If the scheme wasnt activated I dint get an error message stating the same.So for not fault of mine I am charged for Rs1800
When I have sent the message twice for activation and recieved successful registration message also twice.
I am willing to pay the Rs199 but not the excess amount as it is your system error and not mine.
Please look into this matter as soon as possible as it causing a lot of inconvience.