Uber Eats - Promo code not accepted while still valid / horrible customer service

On April 25th I received an email with a promo code, telling me it is valid until May 12th.
On May 6th I place an order through Uber Eats, fill in the code, get an error message that the code is no longer valid. I obviously complain about this.

Answer from Carlos: It seems the promo code you tried to use has expired and is no longer valid on the Uber Eats app. All our promo codes have expiration dates that can be seen when they’re entered in the app. If they’ve already expired, you won’t be able to add it.

Well, I have proof that for sure it is still valid, for 6 more days. So I complain again, with screenshot.

Answer from Flavia: As mentioned previously, the promo code [ *** ] has expired and is no longer valid on the Uber Eats app.
In the future, we would encourage you to double check the promotion expiration date to ensure you have the chance to use it before it expires.
Thank you for your understanding.

Well, I proved it was still valid with a screenshot, this was completely ignored it the answer. So, I calmly explained again what happened and that Uber Eats is making a mistake here.

Answer from Andre: As mentioned previously, the promo code *** has expired and is no longer valid on the Uber Eats app.
In the future, we would encourage you to double check the promotion expiration date to ensure you have the chance to use it before it expires.
Thank you for your understanding.

I was so upset here that I tried one more time, asking to stop sending me template answers but to actually have a look at my mails and screenshots, but then got ignored.