Air India - Refund of the cancelled ticket

I booked the ticket on **th Jan, ****. Then cancelled on **th Jan. I was told by the customer representative that I will get the full refund and they asked me to send the email. Then I again followed up, again they asked me to send the email. Initially, they told me I will get the refund within * days, then told within ** days, then told within ** days, now saying * weeks. All waiting period is over. No refund. Every time a new person holds the phone and says something new. Please help.