Tata Docomo — suddenly stopped network in international roaming

Address:

Hyderabad, Telangana

I am using tata docomo from past 15 years. I am out of country from past 5 years, till date (30-jan-19) i did not faced any issues but suddenly now network not working. Without any prior intimation they stopped the network. I am unable to complain in their site too as they are sending otp to the number as my number don't have network then how can i receive otp. I tried to call international roaming customer care number but they are not ready to take the complain and said send mail to customer care. I sent mail to customer care mail id which they provided i. E [protected]@tatadocomo.com. Reply i received is "this is a business call as our international roaming alliances are not available as of now. So we shall not be able to extend and activate international roaming services".
How can they stop network without any prior intimation and can give silly and foolish answer that this is business call.

Requests you to kindly do needful as my contact number linked to so many things.

Regards,
Balakrishna