If we let people stack discount codes in addition to the 50% discount of a Buy One Get One Free, we'd have to stop doing Buy One Get One Free as it wouldn't be viable. It isn't purely a logistical issue, but also a "it actually costs money to produce and ship products to people" issue, so we won't be offering people 100% discounts on orders just yet...
I’m not asking for stacked discounts. I’m asking for better mathematics. BOGOF separately, discount what is eligible, but in the same order so it isn’t pushed beneath the free shipping threshold. Or stop applying postage to items that only drop below £50 after they are discounted with a voucher. Because then what’s the point of the voucher?
Edit: To expound... In my order I had £55 of Collector's Editions, and 4 items, £40 of BOGOFs.
I expected to pay £20 for the BOGOFS, and £55-10% from the voucher for the Collectors, a saving of £5.50. I expected a final total of £69.50, comfortably over the free shipping threshold.
But the voucher wouldn't activate with the BOGOFs in the basket, I had to try separating the order.
What I would have wound up with that way is £20 for the BOGOF with £3.50 shipping in one order. And the most ridiculous thing, £55 of Collector's Editions over the free shipping threshold, with a 10% voucher applied dropping to £49.50, below the free shipping threshold, so I get another £3.50 applied. I'm now having to spend £7 just to save £5.50 using a voucher.
In other words the voucher was useless to me, and I wound up not using it and just placing a single order for £75. That feels like I'm being taunted for being stingy around the £50 pricepoint.
Solution, get a better algorithm to allow separate and multiple discounts in a single order.
Compromise solution, be realistic when it comes to free shipping and voucher activation thresholds. Drop the free shipping threshhold to £45, so that using a voucher at £50 still offers free shipping, or raise the voucher activation to £55.56 so dropping a 10% voucher into the stack doesn't drop it below £50
Actuually, you'll have to adjust it for 15%, Free shipping at £42.50, or Voucher Activation at £58.82 for the subscribers.