Mts — Refunding the security deposit

Address:

Chennai, Tamil Nadu

got this Mts connection on 10/7/2015. Got activated after I called them up so many times . I have paid 2000 rupees as a security deposit since I am bachelor. Right from the begin inning I didn't get the proper speed as they promised then i called them up so many times but atlast they told since i am living in a place where there are so many houses in it the speed would be like that. Then i requested them to close my account and refund my security deposit and i have paid the usage amount as well(Rs.480). They said they would refund my security deposit but i didnt get any call from them. then after a few days i called them up back again at that time they were saying that i havent paid anything as security deposit i got the bill. i need to get my security deposit back so please take any action.