Tata Indicom — Tata Walky Prepaid

Address:	New Delhi, Delhi, 110018
Website:	www.tatawalky.com/en-in

I had purchased Tata Walky fixed wireless prepaid phone no. 65864649 and been using for many years. For a long period of time my instrument is not working properly on lifting Hand set it gets disconnected. I works fine with speaker. In this connection I have approached Tata indicom showrooms many times to change my instrument. But the showroom men say that company has closed prepaid scheme, you can convert your number into postpaid otherwise no other option is left. Same reply was given by Tata personal at its customercare office at N-44 cannaught Place, New Delhi - 110001. I find it difficult to find its battery as well.
But my Walky No. is quite old. Neither do I want to convert my Walky number into postpaid nor do I want to disconnect it.
Where should I go? Please help me.