Loop Mobile — phone disconnection

hi, . i currently have a loop mobile service on my cell phone. i had activated my bill-desk facility [ its the loop name for electronic clearing facility ] wherein every month, at around the due date, my mobile bill gets directly debited from my bank account. unfortunately even after having this facility activated, loop mobile has disconnected my services 2 times this month, under the pretext that i have over-shot my monthly usage. when asked, they say the monthly max usage will be 1000/-,. my last months bill was about Rs 760, this months usage is only abt 400. they disconnected my cell informing that its not the monthly usage that is 1000/- , but its is the cumulative unpaid bill. i had paid a part payment of Rs 250/- hoping they will reactivate my cell till the bill is deducted from my account, but today they again disconnected my cell saying i have overshot the allowed usage by Rs39/-
the ECS facility it seems is making me a complete fool. i thought it is as good as a post dated cheque, and they can withdraw money from my account on due date. on enquiry with the help line, they replied, that they would have not asked me to pay , if i had given a post dated cheque, but are asking me to pay since it is a bill desk facility. seems loop mobile network feels a person will cheat them with a bill desk facility activated, and a person giving them a Post Dated Cheque will never do it.
i hope some action is taken over Loop mobiles for the inconvenience they have caused to me and possibly numerous consumers, by not informing them that the monthly usage actually means the cumulative unbilled usage, and extorting money from unsuspecting consumers by forcibly disconnecting their services