saks fifth avenue They promised to refund $100 to me, but they didn't. New York NY

I made a purchase on Saks Fifth Avenue on January 29th 2020.  During the check out process, I encounter an issue that I could not apply a promotion code, this promotion code is “SHOPSF”,it takes $100 off after $300 purchase.  I asked their representative, an assistant online named Oscar helped me. I’m planing to have a new account and apply the promotion code, but he said I can go ahead make the purchase, and he will issue a gift card later on.

I have our chat history saved.   But after few months I receive items, i still haven’t received anything regarding the $100 gift card they promised me. They have different excuse every time I call them. First,  they’re saying they gonna issue a gift card, but they didn’t. Second, they’re saying they already issued me a refund, but I don’t see any transactions in my account. Last time I called, they said the promotion already applied on my order, but that is not the truth.

I have an order canceled previously which has the code applied, it says the code is applied, but not the order with issues. I don't know why they're saying this, but they're not honest to their customers.