Canara Bank — refund of rs.24639

I have paid my fees online of a nanodegree of rs.24639 at udacity. The next day i cancelled the same and my refund was initiated by razorpay on 17 may 2018 with arn no. 74332748138813727333808 and transaction id rfnd_abs3wzhrp9x2jt. But i have not received any refund in my bank account. I called the customer care support but they end up the call every time i used to call. I mailed to the head office of canara bank but still there is no reply from them. Kindly look into the matter as i have to pay my college fees.