Tata Motors – Old indica vista model not being serviced

Hello Team,I own the above Tata model and have used it for 16 years. It recently broke down, and I sent it to your authorised service center, George Motors, Waghle Estate Thane West., Thane Maharashtra.
The service center has informed me that since the model is old, they are unable to get the spares from Tata Motors. My car has been lying at the service center for the last 15 days.  
Given the above, can you please help me find who can resolve this issue? I have renewed my vehicle, paying green tax for 5 years more. 
My vehicle number is MH04DW6719. I would appreciate it if you could help me with this.
Regards
Mahesh Shetty9870204919