Terrible support service

I received an email from Ubereats, about 20% discount off chicken items, valid until Sunday, 29th August 2021. I placed an order with a chicken outlet on Friday, 27th August 2021. When I started placing the order, I could see the discounts in the basket, but when I finalised the order, the discounts were not there. I contacted Ubereats support and they kept asking me to send a screenshot of the email I got. At first, I attached the email and then because they kept asking me for a screenshot, I attached the email and sent a screenshot, on Friday afternoon. I get in this morning, to another email, asking me for a screenshot. So I send it again. Then I get a reply to say that the offer had expired. So I lost it and rep****, I had placed the order on Friday 27th, the offer expired on Sunday 29th so they need to resolve the matter. I find their service appalling. I’ve got a good mind and never using them again. Has anyone else had issues like this?