Air India — refund of excess payment collected for upgrade

Address:

29 DEERFIELD RD, 08873

I purchased two tickets from air india to travel in economy class with booking reference pnr ymw6d. I updated the bom - ewr sector to business class on jan 11, 2020, 24 hours before my journey by paying money in inr using the two links sent by air india customer service.
I was asked to pay twice inr 1, 91, 470.00 and inr 86, 010.00 for the update and i understand the second payment inr 86, 010.00, i made is duplicate and excess payment. I contacted the airlines' customer service on the same day and got the confirmation that the payment inr 86, 010.00 i made is, in fact, an excess payment. The airlines customer service promised me that the excess amount would be refunded within 24 hours. But nothing happened.
I sent the request for refund on feb 3, 2020, to [protected]@airindia.in and several reminders from hen on