Myntra.com — provided with goodwill coupon which is not applicable within timeline

During season sale i purchased few products out of which 2 products were lost and myntra has provided me with two goodwill coupon in order to express the apology. The coupon is valid till 8th august, 2018, but whenever i am applying the coupon during checkout against any item it is not applicable. I had a conversation with the customer care executive on 25th july, 2018, who told me that the goodwill coupon is applicable on few products only. Now my complaint is - if the coupon is applicable on few products only then why the link to all those categories been given in the email which the technology team can easily do. The same is evident from the fact that when myntra offers any sale, there is a disclaimer in the end that to avail the sale kindly click the below link for the products that are available in the sale. Now, why not that kind of link been sent to the customer. They hire professionals from every good sector and university, i am sure, then why is this technical glitch?