Very poor service and carelessness @ anna salai reliance web world

I have a reliance post paid connection with no 9380946836. , I lost my device two months back and approached the branch for closing the connection they told you cannot close the connection here , you need to go to the place where u have taken the connection , then I could not close the connection , after one month I approached the same anna salai reliance world they told u pay the amount 700 we will close the connection , I paid and gave my proof and photo to close the connection , the employee name is banu , she gave a number in which I tried 100 times no response , the phone will ring but she never picked up the call 9380664646, now when I called the customer care they are telling as off now unbuckled amount is 438 rs , for the lost modem I paid 700 rs already , and now for their poor service I can’t pay another 700 so kindly help me and take necessary action against the employee ms Banu from anna salai reliance world near TVS bus stop , mount road chennai …
Thank u