Most unhappy that you have not alloed the discount set out on the net.
Surely if you offer such a discount it is up to you to make sure it is actioned and not the customer to seek hard to find boxes.
I have given you the chance to make a decision on this and I may take4 other advice in hand and discuss with trading standards as I assume you work and sell within English Law.
I hope we do not come to t5his and you will be less dogmatic
Yours
Mike Grove