Air India — Flight cancelled but did not inform

My flight from Toronto to Kolkata was cancelled which Air India did not bother to notify me. I happened to call them with another question then they told me about the cancellation. When I asked them to book me for the earliest date available they kept referring me to their ticketing department which went unanswered. The customer service person even hung up on me when I tried to call again. I have emailed them asking for a refund, but pretty sure it will be unanswered too. How to hold such an organization accountable who has absolute disregard towards customer service?