Huge bill charged Rs 1860 Mob:7795494803

Location/place: Bangalore

Name of company/service: Vodafone india

Hi,

I have a vodafone post paid connection(Mob:7795494803) i had taken before 5 months with IBM 325 plan with Rs 1000 credit limit.vodafone gives 1000 minutes(L+N) +100MB data usage with credit limit of Rs 1000.in July month i received bill of Rs 1860 just because my credit limit was increased to Rs 5000 without prior my confirmation.
my credit limit was kept increasing every month and i didnt know at all. i have called several times but there is no response from Vodafone.
just because of the credit limit was Rs5000 i received bill amt of Rs1860 for the month of july. i was never informed before increasing my credit limit.

Please look in to this and take needed action i can not pay this much bill and being a regular&good customer i should have been asked before increasing my credit limit.