Tata Teleservices Limited - Services Not Delivered, Bill Raised, Cash Taken but still legal notice

Ref :-Account No:-*********, Connection Number : *** ********
**th Aug ****

Dear Sir,

We have been using this Tata Docomo connection Land Line (Walky) since around * years and also we have been paying this bills for these services very regularly.
In month of Mar **** – partially services were not available due to problem in the instrument. In Month of April ****, services were completely not available & we requested TATA Docomo helpline technical team. However, there was not any solution.
Post that, during May *st week Mr. Uddhav (Mobile Number : **********) called us and informed us that instrument is not usable as Tata Docomo (Tata Tele Services) have made some changes in technology and hence old instrument will not work on this new changed technology. We need to buy new instrument and for which we have to furnish Aadhar card and also pay Rs.****/- for this.
Mr. Uddhav came to residence and we filled up the form, provided aadhar document and also paid Rs.****/- cash to him. Mr. Uddhav has issued the receipt of the same which is attached here in the email.
Mr. Udhdhav promised us to give us the new instrument with in next ** hours (* days), however, till date (**th Aug ****) instrument has not been received. We have followed up with Mr. Udhdhav and Tata Docomo multiple times. Mr. Udhdhav has stopped picking our phones. Tata Docomo Helpline has not taken any actions against our request. We received the emails from Tata Docomo to activate the instrument but we have not done it in absence of the instrument itself.
On the contarary, to our surprise, we received the bill of Rs.****/- to be paid which was for the period where telephone was not working and we have requested them to resolve the issue.
We have now received the legal notice M**/*********/***, dated **-Jul-****, also about bill of Rs.****/- while our request has been not heard by Tata Teleservices. We have also logged the complaint *********, **-Jul-****, also on Tata Teleservice number. However it still remains unsolved.
We would like Tata Docomo to return our Rs.****/- post deducting Rs.****/- and net balance Rs.***/- with immediate effect. We will be left with no choice but to file the complaint to TRAI for greviance resolution later on.
Regards
Himanshu Dave
+** ***** *****,
dave.himanshu@outlook.com