I used a coupon once then got an order confirmation email that didn't show the coupon. Tried disputing it to get them to apply the coupon, they refused and dema

I used a coupon once then got an order confirmation email that didn't show the coupon. Tried disputing it to get them to apply the coupon, they refused and demanded a screenshot of the order before I clicked checkout which I obviously didn't have since I didn't expect them to scam me. I pressed further and they basically responded saying they spent more time on this issue then allowed and just offered a $5 credit for a future order. After using that I'll never order through doordash again. That $5 coupon just brought the price down to what it would be if I ordered directly from the restaurant.