Gopuff complaint: Credit Coupon

On 7th Feb 2023 I received an out of date product. I contacted Go puff via email and they stated they would give me a £5 credit coupon. They informed me I was not to use coupon for any tobacco or baby product purchases. On the 25 th Feb 2023 I placed an order for some cupboard items and chocolate, to my astonishment the £5 Credit coupon was not applied. So I emailed the customer service and they replied that I received over £8 discount on 25th Feb. I went to my order history and took pictures of the receipt and transactions and forwarded them to Go puff. They kept replying with the same message. I took pictures of all the purchases and totalling amounts where the discounts would show as being deducted, there was NO £5 or any discount ever applied. Go puff today (160323) stated that this is the last time they are replying, I still haven’t received the £5 credit coupon to date.