Vistara Airlines — cancellation of booked and paid flight without notification

I hereby lodge a complaint that the vistara airlines seem to have cancelled the booked & paid flights with pnr: urabwg, booked on 29th october 2018, with e - tickets 228-[protected] & 228-[protected] for me & my wife to travel from chennai (Maa) to kochi and has not notified us regarding the flight cancellation.. Our e-tickets were e mailed to our e mail on 29th oct 2018 & also an offer was sent to upgrade to business class on 10th november 2018 to the same e mail address. Yesterday (18 dec 2018) by chance, i went to vistara website to check up the flight details and found some warnings. From sydney (Australia), i phoned to the vistara assistance, who told me that the flight from chennai (Maa) to kochi has been cancelled.
If i had not gone to vistara booking website, i would not know that the flight has been cancelled and there is no other alternative flight by vistara to travel from chennai to kochi. We are at sydney. We have already booked through a different airline to travel from sydney (Australia) to chennai and from there to go to kochi by vistara air, by flight uk734 at 13:45 on 27th january 2019 from chennai. Now there is no such flight uk734 from chennai to kochi at 13:45 on 27th january 2019 and there is no alternative flight by vistara.
We have booked & paid for hotel at kumarakom at a very high cost and booked for cab too. If i had gone to chennai without knowing all this, i would have been in great trouble. The vistara air has not sent me an e mail even now, in spite of requesting the lady at the phone enquiry as well as sending e mails to vistara air. So far, they have not bothered to send me any communication and now i have to look for a different airline without any written communication from vistara. When, vistara air have cancelled the flight, they never cared to inform us.
We are travelling from sydney to chennai by singapore air & planned to go to cochin by vistara air on 27th january 2019, as booked above.
But the flight has been cancelled and we are left with out any notification regarding this cancellation. If i had not noticed by chance yesterday (18th december 18), you can imagine what would be our plight.
I fail to understand that no body has even now replied my email of 18/12/18 and my request over phone on 18/12/18 to confirm by e mail. Atleast if they confirm the status of the booking in writing, we can try to make alternative arrangement.

My e mail: [protected]@hotmail.com :