I was asked to fill in a survey which I did and received a code for 20% off my next subscription order. I entered the discount code on the subscription page but, as there was already a £10 birthday discount code applied, I got a message telling me only one discount code per order was allowed and was given the choice to swap the discount codes. As the 20% code was worth ~£26 I clicked on swap and was then told the survey code was invalid. The £10 birthday code was not automatically reinstated and I had deleted the email with the code on it.
I contacted the help line and expected them to at least reinstate the birthday code or give me a tenner discount code to re-enter. Five or 6 emails later I was (again) asked to send them the codes (which I didn’t have), attach a screenshot of the subscription page and to add the order number (do future orders have an order number).
I ended up telling them to stuff their tenner. Ironically, their survey was about how they could improve the subscription page.