Airtel — mobile office not disconnect

hello sir i have activared mobile office gprs service on my numbet [protected] and after using it for few days i disconnected it, but even throught i have deactivated that service i am being charged for it daily the rental of 15 rupess so i contacted the costimer care on 121 and they told that the service was active but it was a fault from thier side so we have deactivated the service, but its been 25 days now daily my 15 rupesss r debitated from my acount, so daily my balance is gone to negative, and daily i need to call daily they say the service was active so i have been debited and now they have deactivated but till today i havent seen any improvment, i have got fedup by calling 121 daily and tell them to refund, but its now a 4 day that i havnt recived a refund from airtel each time i call they say that sorry sir we have solved the problem, and u will get ur refund back within 2 hours 4 days have been passed but i havnt got my refund yet, and also how long will they charge me for the service that i dont use at all and once i even thought that if i am paying for the serivice then y not to use it, but then i came to know that my service was not active, and also when i was using the service i used to recive message that u have been debited 14.99 for your vas, but since i have deactivated the service i havnt reciveed any message it automatically get s deducted, plz tell me what to do coz i have fedup by callin 121 now, and even i am not able to talk with any of their head representative yet