[Resolved]  Nykaa — Item missing and gift coupon was not valid

Address: Chennai, Tamil Nadu, 600053

We have placed an order dated 13.10.2016 order no is[protected] worth of Rs.900k+ In that one item Rs.150 has not been delivered they have missed it elsewhere.
when we called the customer care they said they will send on coupon which will be expired dec 31st..From that day we have trying to use that coupon but its showing this message
Coupon code is not valid.
When sending mail to them we are getting the ticket id number and saying within 24 hours they will contact us. but till now no one has contacted or replied through mail.
Your ticket id : 531557
Your ticket id : 534301
and when i had a online chat with Mini she said that it some discount sale that time this coupon will not will be valid only after 16 of December we can use .
when tried now too its showing the same... as not valid coupon.
By giving the coupon they are cheating the customers,
Please take necessary action against them and ask them to solve my problem
else ask them to refund our amount atleast.
Regarding this i tried to call them but their line are always busy and asking us to wait...from morning till evening iam getting the same reply (computerized)
Please solve our problem